Free nucleotides: camp and cgmp, atp, adp, fad, nad. Structure, functions

Enzyme Protein part (apoenzyme) Non-protein part (cofactor) inorganic ion coenzymes prosthetic groups apoenzyme + cofactor = holoenzyme

The role of cofactors can be played by various substances - from simple inorganic ions to complex organic molecules; in some cases they remain unchanged at the end of the reaction, in others they are regenerated as a result of one or another subsequent process.

If the cofactor is presented in the form of an organic molecule (some of these molecules are close to vitamins), then the latter can be tightly associated with the enzyme (in which case it is called a prosthetic group) or weakly associated with it (in which case it is called a coenzyme).

Inorganic ions (enzyme activators)

The ions force the enzyme or substrate molecules into a shape that facilitates the formation of the E-S complex. This increases the chances that the enzyme and substrate will actually react with each other, and therefore increases the rate of the reaction catalyzed by the enzyme.

Example. Salivary amylase activity increases in the presence of chloride ions.

Prosthetic groups (fad, fmn, biotin, heme)

A given organic molecule occupies a position in which it can effectively contribute to the catalytic function of its enzyme.

Example 1. Flavin adenine dinucleotide (FAD) contains riboflavin (vitamin B2), which is the hydrogen acceptor part of its molecule. The function of FAD is associated with the oxidative pathways of the cell, in particular with the respiration process, in which FAD plays the role of one of the carriers in the respiratory chain:

End result: 2H is transferred to A and B. A holoenzyme acts as a link between A and B.

Rice. 8 Vitamin as a component of a prosthetic group (the structure of FAD - flavin adenine dinucleotide) is presented.

Example 2. Heme is an iron-containing prosthetic group. Its molecule has the shape of a flat ring, in the center of which there is an iron atom (porphyrin ring, the same as that of chlorophyll). Heme performs a number of biologically important functions in the body. Electron transfer. As a prosthetic group of cytochromes, heme acts as an electron carrier. By adding electrons, iron is reduced to Fe(II), and by giving them away, it is oxidized to Fe(III). Heme, therefore, takes part in redox reactions due to reversible changes in iron valence. Oxygen transfer. Hemoglobin and myoglobin are two heme-containing proteins that carry oxygen. Iron is found in them in reduced form. Catalytic function. Heme is part of catalases and peroxidases that catalyze the breakdown of hydrogen peroxide and water.

Coenzymes (nad, nadph, coenzyme a, atp)

Example. Nicotinamide adenine dinucleotide (NAD), a derivative of nicotinic acid, can exist in both oxidative and reductive forms. In the oxidative form, NAD plays the role of a hydrogen acceptor during catalysis:

Here E 1 and E 2 are two different dehydrogenases. The end result: 2H is transferred from A to B. Here, a coenzyme acts as a link between two different enzyme systems E 1 and E 2.

Rice. 9 Vitamin as a component of a coenzyme (the structures of NAD, NADP and ATP are presented).

NADH - the basis of energy and life

In its ordinary sense, biological life can be defined as the ability to generate energy within a cell. This energy is high-energy phosphate bonds of chemicals synthesized in the body. The most important high-energy compounds are adenosine triphosphate (ATP), guanosine triphosphate (GTP), creatine phosphoric acid, nicotinamide dinucleotide phosphate (NAD(H) and NADP(H)), phosphorylated carbohydrates.

Nicotinamide adenine dinucleotide (NADH) is a coenzyme present in all living cells and is part of the dehydrogenase group of enzymes that catalyze redox reactions; performs the function of a carrier of electrons and hydrogen, which it receives from oxidizable substances. The reduced form (NADH) is capable of transferring them to other substances.

How to improve performance

What is NADH? Many people call it “an abbreviation for life.” And indeed it is. NADH (nicotinamide adenine dinucleotide coenzyme) is found in all living cells and is a vital element through which energy is produced inside cells. NADH is involved in the production of ATP (ATP). NAD(H), as a universal energy molecule, unlike ATP, can constantly unload mitochondria from excessive accumulation of lactate towards the formation of pyruvate from it, due to stimulation of the pyruvate dehydrogenase complex, which is sensitive specifically to the NAD(H)/NAD ratio.

Chronic Fatigue Syndrome: Focus on Mitochondria

A number of clinical studies have shown the effectiveness of NADH drugs in CFS. The daily dose was usually 50 mg. The most powerful effect occurred after 2-4 weeks of treatment. Fatigue decreased by 37-52%. In addition, such an objective cognitive parameter as concentration of attention improved.

NADH in the treatment of chronic fatigue syndrome

NADH (vitamin B3 coenzyme), present in all living cells, is part of the dehydrogenase group of enzymes that catalyze redox reactions; performs the function of a carrier of electrons and hydrogen, which it receives from oxidizable substances. It is a reserve source of energy in cells. It takes part in almost all energy production reactions, ensuring cell respiration. By influencing the corresponding processes in the brain, the vitamin B3 coenzyme can prevent the death of nerve cells during hypoxia or age-related changes. Takes part in detoxification processes in the liver. Recently, its ability to block lactate dehydrogenase and, thereby, limit ischemic and/or hypoxic damage to the myocardium has been established. Studies of the effectiveness of oral administration in the treatment of chronic fatigue syndrome have confirmed its activating effect on people’s condition.

NADH in sports and medicine: review of foreign literature

We wrote about NADH (nicotinamide adenine dinucleotide phosphate) in previous articles. Now we want to provide information from English-language sources about the role and significance of this substance in energy metabolism in the body, its effect on the nervous system, and its role in the development of a number of pathological situations and prospects for use in medicine and sports. (Download monograph on NADH).

Herbalife Quickspark CoEnzyme 1 (NADH) ATP Energy

Natural Energy at a Cellular Level

Quickspark is a product of the company Herbalife. It is a stable form of Vitamin B3 CoEnzyme1. CoEnzyme1 was found in 1906 in Austria by a scientist called Professor George Birkmayer. CoEnzyme1 was developed for medical purposes and used in the second world war.

NADH (Enada)

Nicotinamide adenine dinucleotide (NADH) is a substance that helps the functionality of enzymes in the body. NADH plays a role in the production of energy and helps produce L-dopa, which the body turns into the neurotransmitter dopamine. NADH is being evaluated for many conditions and may be helpful for enhancing mental functionality and memory.

Cyclic adenosine monophosphate (CAMP)- an ATP derivative that acts as a second messenger in the body, used for intracellular distribution of signals of certain hormones (for example, glucagon or adrenaline) that cannot pass through the cell membrane. Converts a number of inert proteins into enzymes (camp-dependent protein kinases), under the influence of which a number of biochemical reactions occur. reactions (conduction of nerve impulses).

cAMP production is stimulated adrenaline.

Cyclic guanosine monophosphate (cGMP) is a cyclic form of nucleotide formed from guanosine triphosphate (GTP) by the enzyme guanylate cyclase. Education is stimulated acetylcholine.

· cGMP is involved in the regulation of biochemical processes in living cells as a secondary messenger (second messenger). It is characteristic that many of the effects of cGMP are directly opposite to cAMP.

· cGMP activates G-kinase and phosphodiesterase, which hydrolyzes cAMP.

· cGMP is involved in the regulation of the cell cycle. The choice of the cell depends on the cAMP/cGMP ratio: stop dividing (stop in the G0 phase) or continue, moving to the G1 phase.

· cGMP stimulates cell proliferation (division), and cAMP suppresses

Adenosine triphosphate (ATP)- a nucleotide formed by a nitrogenous base adenine, the five-carbon sugar ribose and three phosphoric acid residues. The phosphate groups in the ATP molecule are connected to each other high-energy (macroergic) connections. The bonds between phosphate groups are not very strong, and when they break, a large amount of energy is released. As a result of hydrolytic cleavage of the phosphate group from ATP, adenosine diphosphoric acid (ADP) is formed and a portion of energy is released.

· Together with other nucleoside triphosphates, ATP is the starting product in the synthesis of nucleic acids.

· ATP plays an important role in the regulation of many biochemical processes. Being an allosteric effector of a number of enzymes, ATP, joining their regulatory centers, enhances or suppresses their activity.

· ATP is also a direct precursor for the synthesis of cyclic adenosine monophosphate, a secondary messenger of hormonal signal transmission into the cell.

· The role of ATP as a mediator in synapses and a signal substance in other intercellular interactions is also known

Adenosine Diphosphate (ADP)- a nucleotide consisting of adenine, ribose and two phosphoric acid residues. ADP is involved in energy metabolism in all living organisms; ATP is formed from it by phosphorylation:

ADP + H3PO4 + energy → ATP + H2O.

The cyclic phosphorylation of ADP and the subsequent use of ATP as an energy source form a process that is the essence of energy metabolism (catabolism).

FAD - flavin adenine dinucleotide- a coenzyme that takes part in many redox biochemical processes. FAD exists in two forms - oxidized and reduced, its biochemical function, as a rule, is to transition between these forms.

Nicotinamide adenine dinucleotide (NAD) - dinucleotide consists of two nucleotides connected by their phosphate groups. One of the nucleotides contains adenine as a nitrogenous base, the other contains nicotinamide. Nicotinamide adenine dinucleotide exists in two forms: oxidized (NAD) and reduced (NADH).

· In metabolism, NAD is involved in redox reactions, transferring electrons from one reaction to another. Thus, in cells, NAD exists in two functional states: its oxidized form, NAD+, is an oxidizing agent and takes electrons from another molecule, being reduced to NADH, which then serves as a reducing agent and donates electrons.

· 1. Metabolism of proteins, fats and carbohydrates. Since NAD and NADP serve as coenzymes of most dehydrogenases, they participate in the reactions

during the synthesis and oxidation of fatty acids,

during the synthesis of cholesterol,

exchange of glutamic acid and other amino acids,

carbohydrate metabolism: pentose phosphate pathway, glycolysis,

oxidative decarboxylation of pyruvic acid,

tricarboxylic acid cycle.

· 2. NADH performs a regulatory function because it is an inhibitor of certain oxidation reactions, for example, in the tricarboxylic acid cycle.

· 3. Protection of hereditary information - NAD is a substrate of poly-ADP-ribosylation in the process of cross-linking chromosomal breaks and DNA repair, which slows down necrobiosis and cell apoptosis.

· 4. Protection against free radicals - NADPH is an essential component of the cell's antioxidant system.

NAD, NAD -- a coenzyme present in all living cells, part of the dehydrogenase group of enzymes that catalyze redox reactions; performs the function of a carrier of electrons and hydrogen, which it receives from oxidizable substances. The reduced form (NADH) is capable of transferring them to other substances.

It is a dinucleotide, the molecule of which is built from nicotinic acid amide and adenine, connected to each other by a chain consisting of two D-ribose residues and two phosphoric acid residues; used in clinical biochemistry to determine the activity of blood enzymes.

Rice. 12.

NADP, NADP - a widely distributed coenzyme in nature of some dehydrogenases - enzymes that catalyze redox reactions in living cells. NADP accepts hydrogen and electrons from the compound being oxidized and transfers them to other substances. In the chloroplasts of plant cells, NADP is reduced during light reactions of photosynthesis and then provides hydrogen for the synthesis of carbohydrates during dark reactions. NADP, a coenzyme that differs from NAD by the content of another phosphoric acid residue attached to the hydroxyl of one of the D-ribose residues, is found in all types of cells.

Rice. 13.

FAD, FAD -- a coenzyme that takes part in many redox biochemical processes. FAD exists in two forms, oxidized and reduced, and its biochemical function is typically to transition between these forms.

Rice. 14.

Coenzyme A (coenzyme A, CoA, CoA, HSKoA) - acetylation coenzyme; one of the most important coenzymes that takes part in the transfer reactions of acyl groups during the synthesis and oxidation of fatty acids and the oxidation of pyruvate in the citric acid cycle.

The CoA molecule consists of an adenylic acid residue (1) linked by a pyrophosphate group (2) to a pantothenic acid residue (3), which in turn is linked by a peptide bond to the amino acid β-alanine (4) (these two groups represent the pantothenic acid residue) , connected by a peptide bond to a β-mercaptoethanolamine residue (5).

Insufficient dietary niacin (Figure 10-6) causes a disease in humans called pellagra (from the Italian word meaning “rough skin”). Pellagra is common in many areas of the world where people subsist primarily on corn and eat little meat, milk, or eggs. For the prevention and treatment of pellagra, both nicotinic acid and its amidenicotinamide can be used. To prevent anyone from thinking about the possibility of eating tobacco as a source of this vitamin, nicotinic acid was given another (conventional) name - niacin.

Nicotinamide is a component of two structurally similar coenzymes—nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). The structure of these coenzymes is shown in Fig. 10-6. NADP differs from NAD by the presence of a phosphate group in the molecule. These coenzymes can be found in both oxidized and reduced (NADH and NADPH) forms. The nicotinamide component of these coenzymes plays the role of an intermediate carrier of hydride ion, which is enzymatically cleaved from the substrate molecule under the action of specific dehydrogenases (Fig. 10-7). An example is the reaction catalyzed by malate dehydrogenase, which dehydrogenates malate, converting it to oxaloacetate; this reaction is one of the stages of oxidation of carbohydrates and fatty acids. Malate dehydrogenase also catalyzes the reversible transfer of hydride ion from malate to resulting in the formation of NADH; the second hydrogen atom is split off from the hydroxyl group of the malate molecule in the form of a free ion

A large number of dehydrogenases of this type are known, each of which has specificity for a particular substrate. Some of these enzymes use others as a coenzyme - and still others can function with either of these two coenzymes.

Rice. 10-7. General equation showing how it acts as a coenzyme in enzymatic dehydrogenation reactions. The substrate molecule and reaction products are highlighted in red. Only the icotinamide part of the molecule is depicted; the rest of it is designated by the letter R.

In most dehydrogenases, NAD (or NADP) binds to the protein part of the enzyme only during the catalytic cycle, but there are also enzymes with which these coenzymes are very tightly bound and are constantly present in the active center.