Responsible for the synthesis of atf. ATP and its role in metabolism. Metabolism of fats, their biological role, heat capacity, participation in metabolism. Energy value of fats. Fat deposits
Ways to get energy in the cell
There are four main processes in the cell that ensure the release of energy from chemical bonds during the oxidation of substances and its storage:
1. Glycolysis (stage 2 of biological oxidation) - oxidation of a glucose molecule to two molecules of pyruvic acid, with the formation of 2 molecules ATP and NADH. Further, pyruvic acid is converted to acetyl-SCoA under aerobic conditions, and to lactic acid under anaerobic conditions.
2. β-Oxidation of fatty acids(stage 2 of biological oxidation) - oxidation of fatty acids to acetyl-SCoA, molecules are formed here NADH and FADN 2. ATP molecules in pure form" do not appear.
3. Tricarboxylic acid cycle(TsTK, stage 3 of biological oxidation) - oxidation of the acetyl group (as part of acetyl-SCoA) or other keto acids to carbon dioxide. Full cycle reactions are accompanied by the formation of 1 molecule GTP(which is equivalent to one ATP), 3 molecules NADH and 1 molecule FADN 2.
4. Oxidative phosphorylation(stage 3 of biological oxidation) - NADH and FADH 2 are oxidized, obtained in the reactions of catabolism of glucose, amino acids and fatty acids. At the same time, the enzymes of the respiratory chain on the inner membrane of mitochondria provide the formation greater parts of the cell ATP.
Two ways to synthesize ATP
All nucleosides are constantly used in the cell three phosphates (ATP, GTP, CTP, UTP, TTP) as an energy donor. At the same time, ATP is universal macroerg, participating in almost all aspects of metabolism and cell activity. And it is precisely due to ATP that the phosphorylation of the nucleotides of GDP, CDP, UDP, TDP to the nucleoside is ensured. three phosphates.
In others, the nucleoside three phosphates, there is a certain specialization. So, UTP is involved in the metabolism of carbohydrates, in particular in the synthesis of glycogen. GTP is involved in ribosomes, participates in the formation of peptide bonds in proteins. CTP is used in the synthesis of phospholipids.
The main way to obtain ATP in the cell is oxidative phosphorylation, which occurs in the structures of the inner membrane of mitochondria. At the same time, the energy of hydrogen atoms of NADH and FADH 2 molecules formed in glycolysis, TCA, and fatty acid oxidation is converted into the energy of ATP bonds.
However, there is also another way of phosphorylation of ADP to ATP - substrate phosphorylation. This method is associated with the transfer of macroergic phosphate or the energy of a macroergic bond of a substance (substrate) to ADP. These substances include metabolites of glycolysis ( 1,3-diphosphoglyceric acid, phosphoenolpyruvate), tricarboxylic acid cycle ( succinyl-SCoA) and reserve macroerg creatine phosphate. The energy of hydrolysis of their macroergic bond is higher than 7.3 kcal/mol in ATP, and the role of these substances is reduced to the use of this energy for phosphorylation of the ADP molecule to ATP.
Classification of macroergs
Macroergic compounds are classified according to type of connection, carrying additional energy:
1. Phosphoanhydride connection. All nucleotides have such a bond: nucleoside triphosphates (ATP, GTP, CTP, UTP, TTP) and nucleoside diphosphates (ADP, GDP, CDP, UDP, TDP).
2. Thioether connection. An example is the acyl derivatives of coenzyme A: acetyl-SCoA, succinyl-SCoA, and other compounds of any fatty acid and HS-CoA.
3. Guanidine phosphate connection - present in creatine phosphate, a reserve macroerg of muscle and nervous tissue.
4. Acyl phosphate connection. These macroergs include the glycolysis metabolite 1,3-diphosphoglyceric acid (1,3-diphosphoglycerate). It provides the synthesis of ATP in the reaction of substrate phosphorylation.
5. Enolphosphate connection. The representative is phosphoenolpyruvate, a metabolite of glycolysis. It also provides ATP synthesis in the reaction of substrate phosphorylation in glycolysis.
EVERYONE SHOULD KNOW ABOUT THE ESSENCE OF GEORGY PETRAKOVICH'S WORKS! THERMONUCLEI IN A CELL I will quote in full the interview with Georgy Petrakovich, published in the magazine "Miracles and Adventures" No. 12, 1996, pp. 6-9. Special correspondent of the magazine Vl. Ivanov met with a full member of the Russian Physical Society, surgeon Georgy Nikolayevich Petrakovich, who published sensational works on thermonuclear reactions occurring in living organisms and transformations into them chemical elements. This is much more fantastic than the most daring experiments of alchemists. The conversation is dedicated to the true miracle of evolution, the main miracle of wildlife. We do not agree with the author of the bold hypothesis on everything. In particular, being a materialist, it seems to us that he excludes the spiritual principle from those processes where it, apparently, should be present. Nevertheless, G. Petrakovich's hypothesis interested us, because it intersects with the works of Academician V. Kaznacheev about "cold fusion" in a living cell. At the same time, the hypothesis throws a bridge to the concept noosphere. V. Vernadsky, pointing to the source that continuously feeds the noosphere with energy. The hypothesis is also interesting in that it paves the scientific way to explain the series mysterious phenomena such as clairvoyance, levitation, iridology and others. We ask you to excuse us for some scientific complexity of the conversation for an unprepared reader. The material itself, unfortunately, by its nature cannot be subject to significant simplification. CORRESPONDENT. First, the essence, the salt of a miracle, seemingly incompatible with ideas about living organisms... What kind of strange force operates in us, in the cells of our body? Everything is like a detective story. This power was known, so to speak, in a different capacity. She acted incognito, as if under a mask. They spoke and wrote about it like this: hydrogen ions. You understood and called it differently: protons. These are the same hydrogen ions, the bare nuclei of its atoms, positively charged, but at the same time they are elementary particles. Biophysicists have not noticed that Janus is two-faced. Is not it? Can you elaborate on this? G.N. PETRAKOVICH. A living cell receives energy as a result of ordinary chemical reactions. So considered the science of cellular bioenergetics. As always, electrons take part in the reactions, it is their transitions that provide the chemical bond. In tiny bubbles irregular shape - mitochondria of the cell - oxidation occurs with the participation of electrons. This is the postulate of bioenergetics. Here is how this postulate is presented by the country's leading bioenergetician, Academician of the Russian Academy of Sciences V.P. Skulachev: "In order to experiment with the use of nuclear energy, nature had to create a person. As for the intracellular energy mechanisms, they extract energy exclusively from electronic transformations, although the energy effect here is immeasurably small compared to thermonuclear processes." "Exclusively from electronic transformations ..." This is a delusion! Electronic transformations are chemistry and nothing more. It is thermonuclear reactions that underlie cellular bioenergy, and it is the proton, also known as the hydrogen ion - a heavy charged elementary particle - that is the main participant in all these reactions. Although, of course, the electron also takes a definite and even important part in this process, but in a different role, completely different from the role assigned to it by scientific specialists. And what is most surprising: in order to prove all this, it turns out that it is not necessary to conduct any complex research, research. Everything lies on the surface, everything is presented in the same indisputable facts, observations, which the scientists themselves obtained with their hard work. It is only necessary to reflect unbiasedly and in depth on these facts. Here is an indisputable fact: it is known that protons are "ejected" from mitochondria (the term is widely used by specialists, and it sounds like a disregard for these workaholic particles, as if it were waste, "garbage") into the space of the cell (cytoplasm). Protons move unidirectionally in it, that is, they never return, in contrast to the Brownian movement in the cell of all other ions. And they move in the cytoplasm at a tremendous speed, exceeding the speed of movement of any other ions many thousands of times. Scientists do not comment on this observation in any way, but they should be seriously thought about. If protons, these charged elementary particles, move in the space of the cell with such a huge speed and "purposefully", it means that the cell has some mechanism for their acceleration. Undoubtedly, the acceleration mechanism is located in the mitochondria, from where protons are initially "ejected" with great speed, but what is its nature ... Heavy charged elementary particles, protons, can be accelerated only in a high-frequency alternating electromagnetic field - in a synchrophasotron, for example. So, molecular synchrophasotron in mitochondria? no matter how strange it may seem, yes: the subminiature natural synchrophasotron is located precisely in a tiny intracellular formation, in mitochondria! Protons, having fallen into a high-frequency alternating electromagnetic field, lose the properties of the chemical element hydrogen for the entire time they stay in this field, but they exhibit the properties of heavy charged elementary particles. "For this reason, in a test tube it is impossible to fully repeat the processes that constantly occur in living For example, in a test tube of a researcher, protons are involved in oxidation, and in a cell, although free-radical oxidation occurs, peroxides are not formed. Meanwhile, scientists are guided precisely by "test-tube" experience when they study processes in a living cell. Protons accelerated in the field easily ionize atoms and molecules, "knocking out" electrons from them. At the same time, molecules, becoming free radicals, acquire high activity, and ionized atoms (sodium, potassium, calcium, magnesium and other elements) form e electric and osmotic potentials (but of a secondary order dependent on protons). CORRESPONDENT. It's time to draw the attention of our readers to the fact that a living cell invisible to the eye is more complicated than any gigantic installation, and what is happening in it cannot yet be even approximately reproduced. Perhaps galaxies - on a different scale, of course - are the simplest objects of the universe, just as cells are the elementary objects of a plant or animal. Perhaps the levels of our knowledge about cells and galaxies are roughly equivalent. But the most striking thing is that the thermonucleus of the Sun and other stars corresponds to the cold thermonucleus of a living cell, or, more precisely, of its individual sections. The analogy is complete. Everyone knows about the hot fusion of stars. But only you can tell about the cold fusion of living cells. G.N. PETRAKOVICH. Let's try to imagine the most important events at this level. Being heavily charged elementary particle, whose mass exceeds the mass of an electron by 1840 times, the proton is a part of all atomic nuclei without exception. Being accelerated in a high-frequency alternating electromagnetic field and being in the same field with these nuclei, it is able to transfer its kinetic energy to them, being the best energy carrier from the accelerator to the consumer - the atom. Interacting in the cell with the nuclei of target atoms, it transfers to them in parts - by elastic collisions - the kinetic energy acquired by it during acceleration. And having lost this energy, it is eventually captured by the nucleus of the nearest atom (inelastic collision) and enters into this nucleus as an integral part. And this is the way to the transformation of elements. In response to the energy received during an elastic collision with a proton, its own quantum of energy is ejected from the excited nucleus of the target atom, which is characteristic only of the nucleus of this particular atom, with its own wavelength and frequency. If such interactions of protons occur with many nuclei of atoms that make up, for example, any molecule; then there is an emission of a whole group of such specific quanta in a certain frequency spectrum. Immunologists believe that tissue incompatibility in a living organism manifests itself already at the molecular level. Apparently, the difference in a living organism between "one's own" protein molecule and a "foreign" one, with their absolute chemical identity, occurs in these very specific frequencies and spectra, to which the "sentinel" cells of the body - leukocytes - react differently. CORRESPONDENT. An interesting incidental result of your proton-nuclear theory! Even more interesting is the process that the alchemists dreamed of. Physicists have pointed to the possibility of obtaining new elements in reactors, but this is very difficult and expensive for most substances. A few words about the same at the cell level... G.N. PETRAKOVICH. The capture of a proton that has lost its kinetic energy by the nucleus of a target atom changes the atomic number of this atom, i.e. the “capturing” atom is capable of changing its nuclear structure and becoming not only an isotope of a given chemical element, but in general, given the possibility of multiple “capture” of protons, take a different place than before in the periodic table: and in some cases even not the closest to the former. Essentially, we are talking about nuclear fusion in a living cell. It must be said that such ideas have already excited the minds of people: there have already been publications about the work of the French scientist L. Kervran, who discovered such a nuclear transformation in the study of laying hens. True, L. Kervran believed that this nuclear synthesis of potassium with a proton, followed by the production of calcium, is carried out with the help of enzymatic reactions. But, proceeding from what has been said above, it is easier to imagine this process as a consequence of internuclear interactions. In fairness, it should be said that M.V. Volkenstein generally considers the experiments of L. Kervran an April Fool's joke of his cheerful American scientists colleagues. The first thought about the possibility of nuclear fusion in a living organism was expressed in one of the fantastic stories of Isaac Asimov. One way or another, paying tribute to both, and to the third, we can conclude that, according to the stated hypothesis, internuclear interactions in a living cell are quite possible. And the Coulomb barrier will not be an obstacle: nature has managed to bypass this barrier without high energies and temperatures, softly and gently, CORRESPONDENT. You think that a vortex electromagnetic field arises in a living cell. It holds protons as if in its grid and accelerates them, accelerates them. This field is emitted, generated by electrons of iron atoms. There are groups of four such atoms. They are called by specialists like this: gems. Iron in them is divalent and trivalent. And both of these forms exchange electrons, the jumps of which generate the field. Its frequency is incredibly high, according to your estimate of 1028 hertz. It far exceeds the frequency of visible light, which is also usually generated by jumps of electrons from one atomic level to another. Don't you think that this estimate of the frequency of the field in the cell is too high for you? G.N. PETRAKOVICH. Far from it. CORRESPONDENT. Your answer is clear to me. After all, it is very high frequencies and the corresponding small wavelengths that are associated with great energy quants. So, ultraviolet with its short waves is stronger than ordinary rays of light. Very short waves are needed to accelerate protons. Is it possible to test the proton acceleration scheme itself and the frequency of the intracellular field? G.N. PETRAKOVICH. So, the discovery: in the mitochondria of cells, an ultra-high-frequency, ultra-short-wave variable is generated electricity and according to the laws of physics, according to him - ultra-short-wave and super-high-frequency alternating electromagnetic field. The shortest wavelength and highest frequency of all variable electromagnetic fields in nature. Instruments that could measure such a high frequency and such a short wave have not yet been created, so such fields do not yet exist for us at all. And the discovery does not yet exist ... Nevertheless, let's turn again to the laws of physics. According to these laws, point variable electromagnetic fields do not exist independently, they instantly merge with each other at the speed of light by synchronization and resonance, which significantly increases the voltage of such a field. The point electromagnetic fields formed in electromagnetism by moving electrons merge, then all the fields already mitochondria merge. A combined microwave, ultra-short-wave alternating field is formed for the entire mitochondrion. It is in this field that the protons are held. But mitochondria in one cell are not two or three - in each cell there are tens, hundreds, and in some - even thousands, and in each of them this ultra-short-wave field is formed; and these fields tend to merge with each other, all with the same synchronization and resonance effect, but already in the entire space of the cell - in the cytoplasm. This desire of the alternating electromagnetic field of the mitochondrion to merge with other similar fields in the cytoplasm is the very "draught force", the energy that "throws" protons from the mitochondrion into the cell space with acceleration. This is how the intra-mitochondrial "synchrophasotron" works. It should be remembered that protons move towards the nuclei of target atoms in a cell in a significantly enhanced field - so short-wavelength that it can easily, as if along a waveguide, pass between the nearest atoms, even in a metal lattice. This field will easily "carry" with it a proton, whose size is a hundred thousand times smaller than any atom, and is so high-frequency that it does not lose its energy at all. Such a superpermeable field will also excite those protons that are part of the nucleus of the target atom. And most importantly, this field will bring the "incoming" proton so close to them that it will allow this "incoming" proton to give part of its kinetic energy to the nucleus. Most a large number of Energy is released during alpha decay. At the same time, alpha particles are ejected from the nucleus with great speed, which are firmly bound two protons and two neutrons (that is, the nuclei of helium atoms). In contrast to a nuclear explosion, a "cold fusion" does not accumulate a critical mass in the reaction zone. Decay or synthesis can stop immediately. No radiation is observed, since alpha particles outside the electromagnetic field immediately turn into helium atoms, and protons into molecular hydrogen, water or peroxides. At the same time, the body is capable of creating the chemical elements it needs from other chemical elements by means of a "cold fusion" and neutralizing substances that are harmful to it. Holograms are formed in the zone where the "cold fusion" occurs, reflecting the interactions of protons with the nuclei of target atoms. Ultimately, these holograms in an undistorted form are taken out by electromagnetic fields into the noosphere and become the basis of the energy-informational field of the noosphere. A person is able arbitrarily, with the help of electromagnetic lenses, the role of which in a living organism is played by piezocrystal molecules, to focus the energy of protons, and especially alpha particles, into powerful beams. At the same time, demonstrating phenomena that stagger the imagination: lifting and moving incredible weights, walking on hot stones and coals, levitation, teleportation, telekinesis, and much more. It cannot be that everything in the world disappears without a trace, on the contrary, one should think that there is a kind of global "bank", a global biofield, with which the fields of all who lived and live on Earth have merged and are merging. This biofield can be represented by a super-powerful, super-high-frequency, super-short-wave and super-penetrating variable electromagnetic field around the Earth (and thus around and through us). In this field, the nuclear charges of proton holographic "films" about each of us are kept in perfect order - about people, about bacteria and elephants, about worms, about grass, plankton, saxaul, who lived once and live now. Those who live now and support this biofield with the energy of their field. But only rare units have access to its informational treasures. This is the memory of the planet, its biosphere. The still unknown global biofield has colossal, if not limitless, energy, we all bathe in the ocean of this energy, but we don’t feel it, just as we don’t feel the air around us, and therefore we don’t feel that it exists around us ... Its role will increase . This is our reserve, our support. CORRESPONDENT. By itself, this field of the planet, however, will not replace working hands and a creative mind. It only creates the prerequisites for the manifestation of human abilities.
G.N. PETRAKOVICH. Another aspect of the topic. Our eyes, if not a mirror of the soul, then their transparent media - the pupil and the iris - are still screens for the topographic "movie" constantly coming from us. "Whole" holograms fly through the pupils, and in the irises, protons carrying a significant charge of kinetic energy continuously excite the molecules in the pigment clumps. They will excite them until everything is in order in the cells that "sent" their protons to these molecules. Cells will die, something else will happen to them, to the organ - the structure in lumps of pigments will immediately change. This will be clearly recorded by experienced iridologists: they already know for sure - from the projections in the iris - which organ is sick and even with what. Early and accurate diagnosis! Some physicians are not very favorable to their colleagues-iridodiagnostics, considering them almost charlatans. In vain! Iridology, as simple, accessible, cheap, easily translated into mathematical language, and most importantly - accurate and early method diagnosis of various diseases in the near future, the "green light" shines. The only downside method was the lack of a theoretical basis. Its foundation is outlined above. CORRESPONDENT. I think it would be necessary for our readers to explain the process of formation of holograms of each individual. You will do it better than me. G.N. PETRAKOVICH. Let us imagine interactions of accelerated protons with some large bulk (three-dimensional) molecule in a cell, occurring very quickly. For such interactions with the nuclei of the target atoms that make up this large molecule, many protons will be consumed, which, in turn, will leave, in turn, a volumetric, but "negative" trace in the form of vacuum, "holes" in the proton beam, too. This trace will be the real hologram, which embodies and retains a part of the structure of the molecule itself that reacted with protons. A series of holograms (which happens "in nature") will display and preserve not only the physical "appearance" of the molecule, but also the order of physical and chemical transformations of its individual parts and the entire molecule as a whole over a certain period of time. Such holograms, merging into larger volumetric images, can display the life cycle of the entire cell, many neighboring cells, organs and body parts - the whole body. There is another consequence. Here it is. In wildlife, regardless of consciousness, we communicate primarily with fields. In such communication, having entered into resonance with other fields, we risk losing, partially or completely, our individual frequency (as well as purity), and if in communication with green nature this means "dissolve in nature", then in communication with people, especially with those who have a strong field, it means to partially or completely lose their individuality - to become a "zombie" (according to Todor Dichev). technical apparatus There is no “zombie” under the program and it is unlikely that they will ever be created, but the impact of one person on another in this regard is quite possible, although, from the standpoint of morality, it is unacceptable. In self-care, this should be considered, especially when it comes to noisy collective actions, in which it is not reason and not even true feeling that always prevails, but fanaticism - the sad child of malicious resonance. The flow of protons can only increase due to merging with other flows, but in no way, in contrast to, for example, an electron flow, not mix - and then it can carry complete information already about whole organs and tissues, including - and about such a specific organ like the brain. Apparently, we think in programs, and these holograms are able to transmit a stream of protons through our eyes - this is evidenced not only by the "expressiveness" of our eyes, but also by the fact that animals are able to assimilate our holograms. In confirmation of this, one can refer to the experiments of the famous trainer V.L. Durov, in which Academician V.M. Bekhterev. In these experiments, a special commission immediately came up with any tasks that were feasible for them, V.L. Durov right there" hypnotic gaze"assigned these tasks to the dogs (at the same time, as he said, he himself, as it were, became a" dog "and mentally completed tasks with them), and the dogs exactly fulfilled all the instructions of the commission. By the way, photographing hallucinations can be associated with holographic thinking and transmission of images by a stream of protons through a glance. important point: information-carrying protons "mark" the protein molecules of their body with their energy, while each "labeled" molecule acquires its own spectrum, and with this spectrum it differs from exactly the same in chemical composition molecule, but belonging to a "foreign" body. The principle of mismatch (or coincidence) in the spectrum of protein molecules underlies immune reactions organism, inflammation, as well as tissue incompatibility, as we have already mentioned. The olfaction mechanism is also built on the principle of spectral analysis of molecules excited by protons. But in this case, all molecules of the substance in the air inhaled through the nose are irradiated with protons with an instant analysis of their spectrum (the mechanism is very close to the mechanism of color perception). But there is a "work" that is performed only by a high-frequency alternating electromagnetic field - this is the work of the "second", or "peripheral" heart, about which a lot was written at one time, but whose mechanism no one has yet discovered. This is a special topic for conversation. To be continued... | Parameter name | Meaning |
| Article subject: | ATP SYNTHESIS. |
| Rubric (thematic category) | Chemistry |
COMPLEX IV.
Complex IV is commonly referred to as cytochrome oxidase. It is able to capture 4 protons from the matrix. He sends two of them to the intermembrane space, and transfers the rest to the formation of water.
Due to the multistage transfer, energy in the respiratory chain is not released instantly, but gradually (in small portions) with each transfer reaction. These portions of energy are not the same in size. Their value is determined by the difference between the ORP of two neighboring carriers. If this difference is small, then little energy is released - it is dissipated in the form of heat. But at several stages it is enough to synthesize macroergic bonds in the ATP molecule. These stages are:
1) NAD / FAD - potential difference 0.25V.
2) Cytochromes b/cc 1 - 0.18V
3) aa 3 / O -2 - 0.53V.
This means that for every pair of hydrogen atoms taken from the substrate, the synthesis of 3 ATP molecules is possible.
ADP + F + ENERGY -------> ATP + H 2 O
A macroergic bond is such a covalent bond, during the hydrolysis of which at least 30 kJ / mol of energy is released. This connection is denoted by ~ .
The synthesis of ATP due to the energy released in the MTO system is commonly called OXIDATIVE PHOSPHORYLATION. The main role of ATP is to provide energy for the process of ATP synthesis.
To assess the efficiency of the MTO system during oxidation, we calculate P/O RATIO. It shows how many molecules of inorganic phosphate have attached to ADP per one oxygen atom.
For the main (full) circuit P / O = 3 (10H + / 2H + +1H+ ) = 3,3 (round up to 3rd)), coefficient useful action systems - 65%, for shortened P/O=2 (6H + /2H +(costs for the release of ATP from the complex with the enzyme) +1H+(cost of transporting phosphate) ) = 2 , for the shortest P/O=1 (4H + /2H +(costs for the release of ATP from the complex with the enzyme) +1H+(cost of transporting phosphate) ) = 1 .
The MTO system consumes 90% of the oxygen entering the cell. At the same time, 62 kilograms of ATP are formed per day. But the cells of the body contain only 20-30 grams of ATP. For this reason, the ATP molecule is hydrolyzed per day and synthesized again on average 2500 times ( average duration life ATP molecules- half a minute).
MAIN PROCESSES FOR WHICH ATP ENERGY IS USED:
1. Synthesis of various substances.
2. active transport(transport of substances across a membrane against their concentration gradient). 30% of the total amount of ATP consumed falls on Na +, K + -ATPase.
3. mechanical movement(muscle work).
In the inner membrane of mitochondria there is an integral protein complex - H + -dependent ATP synthase seu H + -dependent ATPase(two different names are associated with the complete reversibility of the catalyzed reaction), which has a significant molecular weight - more than 500 kDa. Consists of two subunits: FO and F 1 .
F 1 is a mushroom-shaped outgrowth on the matrix surface of the inner mitochondrial membrane, while FO penetrates this membrane through and through. A proton channel is located in the depth of FO, allowing protons to return back to the matrix along the gradient of their concentrations.
F 1 is able to bind ADP and phosphate on its surface with the formation of ATP - without energy expenditure, but always in combination with the enzyme. Energy is needed only to release ATP from this complex. This energy is released as a result of the proton current through the FO proton channel.
In the respiratory chain, conjugation absolutely: No substance can be oxidized without the reduction of another substance.
But in the synthesis of ATP, the conjugation is one-way: oxidation can occur without phosphorylation, and phosphorylation never occurs without oxidation. This means that the MTO system can work without ATP synthesis, but ATP must not be synthesized if the MTO system does not work.
ATP SYNTHESIS. - concept and types. Classification and features of the category "ATP SYNTHESIS." 2017, 2018.
Hydrogen atoms removed from substrates in the Krebs cycle, as a result β -oxidation of HFA, as well as pyruvate dehydrogenase, glutamate dehydrogenase and some other reactions, enter the respiratory chain of enzymes (Fig. 23), which is otherwise called electron transport chain .
The proton and electron transfer process (hydrogen atom = hydrogen proton (H+) + electron (e)) begins with the transfer of hydrogen atoms from the reduced form of NAD or FAD.
Rice. 23. Scheme of the electron transport chain
Reduced NAD donates hydrogens to a flavoprotein whose coenzyme is FMN, while reduced FAD always donates hydrogens to the coenzyme Q. After coenzyme Q only electrons are transported through the cytochrome system; the role of the final - terminal - electron acceptor is performed by oxygen. Before studying the operation of the electron transport chain in more detail, let's get acquainted with chemical structure its individual components.
As noted earlier, all components of the electron transport chain are enzymes that catalyze redox processes.
Flavoprotein is the first enzyme to accept protons and electrons from primary dehydrogenase, an enzyme that removes hydrogen atoms directly from the substrate. The coenzyme of the flavoprotein is FMN. With the structure and redox reactions of FMN, we met earlier (see Chapter 4). This enzyme is closely associated with iron-sulfur proteins.
Iron-sulfur proteins have a small molecular weight (about 10 kDa). They contain non-heme iron bound to the sulfur atoms of cysteine residues. On fig. 24 shows only one of options complex of an iron atom with sulfur atoms that exist in proteins containing non-heme iron.
Rice. 24. Scheme of the formation of a complex of an iron atom with sulfur atoms in iron-sulfur proteins
These proteins are involved in the transfer of protons and electrons and are thought to be involved in several steps. However, the mechanism by which iron-sulfur proteins undergo reversible oxidation-reduction is still not clear.
coenzyme Q or ubiquinone is dissolved in the lipid portion of the inner mitochondrial membrane. Ubiquinone can diffuse both across and along the membrane. It is the only non-protein-bound component of the respiratory chain; for this reason, it cannot be classified as an enzyme. coenzyme Q accepts two hydrogen protons and two electrons from iron-sulfur proteins, turning into hydroquinone:
Cytochromes are hemoproteins. Currently, about 30 different cytochromes are known. All of them, depending on their ability to absorb light, are divided into classes, denoted by lowercase letters - a, b, c etc. Within each class there are certain types cytochromes, designating them with digital indices - b, b 1 , b 2 etc.
Cytochromes differ from each other in the structure of the theme, the structure of the polypeptide chain and the way the theme is attached to it. Figure 25 shows the structure of the topic, which is part of all cytochromes b.
Cytochromes are stained red-brown; The color is due to the presence of a metal cation. Cytochrome classes b and With contain iron cations in their composition, and cytochromes of the class a - copper cations.
Cytochromes a and a 3 form a complex called cytochrome oxidase. The unique feature of the complex a a 3 is that this system of cytochromes donates electrons directly to oxygen.
The transfer of electrons along the chain of cytochromes includes reversible reactions:
Fe 3+ + e ----→ ←---- Fe 2+ and Cu 2+ + e ----→ ←---- Cu +
Having become acquainted with the characteristics of the components of the electron transport chain and with the redox reactions occurring in it, let's move on to the consideration of the process, which is the main one in the accumulation of energy in the form of ATP.
Rice. 25. Structure theme of cytochrome b
The mechanism of conjugation of respiration with ADP phosphorylation. The transport of protons and electrons from reduced NAD to molecular oxygen is an exergonic process:
NADH + H + + ½O 2 → OVER + + H 2 O + energy
If we further simplify the recording of this process, then we get the equation for the reaction of hydrogen combustion in oxygen, which is known to everyone from school:
H 2 + ½O 2 → H 2 O + energy
The only difference is that during the combustion reaction, energy is immediately released completely, and in the respiratory chain, due to the fact that it is divided into several redox reactions, a gradual release of energy occurs. This energy is stored in the phosphate bonds of ATP and used for the life of cells.
The first result of the operation of the electron transport chain is the formation of endogenous water, in the molecule of which the hydrogen atoms are hydrogens removed from the substrates by the corresponding dehydrogenases, and the oxygen atom is the terminal electron acceptor (see Fig. 23). Having taken on 2 electrons, it turns into a reactive anion (O 2-), which immediately interacts with hydrogen protons "ejected" by the coenzyme Q. The formation of endogenous water occurs in the mitochondrial matrix.
The mechanism of conjugation of respiration with ADP phosphorylation was developed by the English biochemist P. Mitchell, whose hypothesis was called proton-motive or chemiosmotic. In our country, P. Mitchell's hypothesis was developed in the works of V.P. Skulachev.
According to chemiosmotic hypothesis the energy of proton and electron transfer along the respiratory chain is initially concentrated in the form of a proton potential created by the movement of charged hydrogen protons across the membrane. The transport of protons back across the membrane is associated with ADP phosphorylation, which is carried out by proton-dependent ATP synthase (H + = ATPase).
Because the driving force ATP synthesis is the proton potential, let's take a closer look at its formation.
Along with the transfer of protons and electrons along the respiratory chain, an additional release of hydrogen protons from the matrix into the intermembrane space takes place. Hydrogen protons arise during the dissociation of water in the matrix:
H 2 O -→ ←- H + + OH -
The transport of hydrogen protons across the inner mitochondrial membrane is thought to be carried out by proton translocases. As a result of this transfer, the membrane is negatively charged from the side of the matrix (due to the remaining negatively charged hydroxyls), and positively charged from the side of the intermembrane space (due to the transfer of positively charged hydrogen protons). As a result of this distribution of charges, an electric potential arises, denoted Δψ (delta psi). And due to the difference in the concentration of hydrogen protons on both sides of the inner membrane of mitochondria, a chemical gradient of protons, denoted ApH, is created. Both emerging potentials create an electrochemical transmembrane gradient of protons (ΔμН +) on the membrane, therefore ΔμН + = Δψ + ΔрН
Synthesis of ATP. The membrane on which the electrochemical transmembrane gradient of protons is created is called energized . The energized membrane tends to discharge by pumping protons from the intermembrane space back into the matrix (Fig. 26). This process is carried out with the help of proton-dependent ATPase.
Rice. 26. Synthesis of ATP coupled with an electron transport chain
H + -ATPase is built into the inner membrane of mitochondria. It looks like a mushroom and consists of two protein factors F 0 and F 1 (Fig. 27). The F0 factor permeates the entire thickness of the inner mitochondrial membrane. The spherical part protruding into the mitochondrial matrix is the F 1 factor. The structure, properties and functions of these protein factors are completely different.
Factor F 0 consists of three hydrophobic polypeptide chains of different structure. This factor performs the function of a proton-conducting channel through which hydrogen protons get to the factor F 1 .
Factor F 1 is a water-soluble part of H + -ATPase and is a protein complex consisting of nine subunits of five different types. One epimolecule of factor F 1 contains 3 α , 3β and one subunit γ , δ , ε (α 3 β 3 γδε ). Factor F 1 carries out the synthesis of ATP from ADP and phosphoric acid. ADP and ATP binding sites are located in the subunits α and β each of which can hold one molecule of ADP or ATP. According to X-ray diffraction analysis, ADP and ATP binding sites are located at the junction of subunits α and β . Subunit β performs a catalytic function in the synthesis of ATP (Fig. 27).
Rice. 27. Structure of proton-dependent ATPase
There are several concepts explaining the mechanism of ATP formation through H + -ATPase. All concepts consider hydrogen protons that enter through the proton-conducting channel to factor F 1 as activators of various processes leading to the formation of ATP from ADP and phosphoric acid.
Adenosine triphosphoric acid-ATP- an obligatory energy component of any living cell. ATP is also a nucleotide consisting of the nitrogenous base of adenine, the sugar of ribose, and three residues of the phosphoric acid molecule. This is an unstable structure. AT metabolic processes phosphoric acid residues are sequentially cleaved from it by breaking the energetic, but fragile bond between the second and third phosphoric acid residues. The detachment of one molecule of phosphoric acid is accompanied by the release of about 40 kJ of energy. In this case, ATP passes into adenosine diphosphoric acid (ADP), and with further cleavage of the phosphoric acid residue from ADP, adenosine monophosphoric acid (AMP) is formed.
Schematic diagram of the structure of ATP and its transformation into ADP ( T.A. Kozlova, V.S. Kuchmenko. Biology in tables. M., 2000 )
Consequently, ATP is a kind of energy accumulator in the cell, which is "discharged" when it is split. The breakdown of ATP occurs during the reactions of synthesis of proteins, fats, carbohydrates and any other vital functions of cells. These reactions go with the absorption of energy, which is extracted during the breakdown of substances.
ATP is synthesized in mitochondria in several stages. The first one is preparatory - proceeds stepwise, with the involvement of specific enzymes at each step. At the same time, complex organic compounds are broken down into monomers: proteins - into amino acids, carbohydrates - into glucose, nucleic acids - into nucleotides, etc. Breaking bonds in these substances is accompanied by the release a small amount energy. The resulting monomers under the action of other enzymes can undergo further decomposition with the formation of simpler substances up to carbon dioxide and water.
Scheme Synthesis of ATP in the mitochondria of the cell
EXPLANATIONS TO THE SCHEME CONVERSION OF SUBSTANCES AND ENERGY IN THE PROCESS OF DISSIMILATION
Stage I - preparatory: complex organic matter under the action of digestive enzymes, they break down into simple ones, while only thermal energy is released.
Proteins -> amino acids
Fats- >
glycerin and fatty acid
Starch ->glucose
Stage II - glycolysis (oxygen-free): carried out in the hyaloplasm, not associated with membranes; it involves enzymes; glucose is broken down:
In yeast fungi, the glucose molecule, without the participation of oxygen, is converted into ethyl alcohol and carbon dioxide (alcoholic fermentation):
In other microorganisms, glycolysis can be completed with the formation of acetone, acetic acid etc. In all cases, the breakdown of one glucose molecule is accompanied by the formation of two ATP molecules. During the oxygen-free breakdown of glucose in the form of a chemical bond, 40% of the anergy is retained in the ATP molecule, and the rest is dissipated in the form of heat.
Stage III - hydrolysis (oxygen): carried out in mitochondria, associated with the mitochondrial matrix and the inner membrane, enzymes participate in it, lactic acid undergoes cleavage: CsH6Oz + ZH20 --> 3CO2 + 12H. CO2 (carbon dioxide) is released from mitochondria into environment. The hydrogen atom is included in a chain of reactions, the end result of which is the synthesis of ATP. These reactions go in the following order:
1. The hydrogen atom H, with the help of carrier enzymes, enters the inner membrane of mitochondria, which forms cristae, where it is oxidized: H-e--> H+
2. Hydrogen proton H+(cation) carried by carriers to outer surface crystal membranes. For protons, this membrane is impermeable, so they accumulate in the intermembrane space, forming a proton reservoir.
3. Hydrogen electrons e transferred to inner surface membranes of cristae and immediately attach to oxygen with the help of the oxidase enzyme, forming a negatively charged active oxygen (anion): O2 + e--> O2-
4. Cations and anions on both sides of the membrane create an oppositely charged electric field, and when the potential difference reaches 200 mV, the proton channel begins to operate. It occurs in the enzyme molecules of ATP synthetase, which are embedded in the inner membrane that forms the cristae.
5. Hydrogen protons through the proton channel H+ rush into the mitochondria, creating high level energy, most of which goes to the synthesis of ATP from ADP and P (ADP + P -\u003e ATP), and protons H+ interact with active oxygen, forming water and molecular 02:
(4Н++202- -->2Н20+02)
Thus, O2, which enters the mitochondria during the respiration of the organism, is necessary for the addition of hydrogen protons H. In its absence, the entire process in mitochondria stops, since the electron transport chain ceases to function. General reaction Stage III:
(2CsHbOz + 6Oz + 36ADP + 36F ---> 6C02 + 36ATP + + 42H20)
As a result of the breakdown of one glucose molecule, 38 ATP molecules are formed: at stage II - 2 ATP and at stage III - 36 ATP. The resulting ATP molecules go beyond the mitochondria and participate in all cell processes where energy is needed. Splitting, ATP gives off energy (one phosphate bond contains 40 kJ) and returns to the mitochondria in the form of ADP and F (phosphate).