ADENOSINEPHOSPHORIC ACIDS

From Big Medical Encyclopedia

ADENOSINEPHOSPHORIC ACIDS (adenylic nucleotides) — biologically active agents representing phosphoric ethers of adenosine. Among And. to. distinguish monophosphoric derivatives of adenosine: adenosinemonophosphoric, or adenylic, acids (AMF) and polyphosphoric derivatives (adenosine diphosphoric — ADF and adenosine triphosphoric — ATP) acids, and also the derivatives containing a bigger number of the remains phosphoric to - you among which adenosinetetraphosphoric and adenosinepentaphosphoric acids are described. At full hydrolysis And. to. give adenine (see. Purine bases ), ribose (see) and phosphoric to - that. At incomplete hydrolysis it is possible to receive adenosine and the corresponding ribozofosforny acids. The rest phosphoric to - you in adenylic acids is connected by an ester group to a hydroxyl of a ribose in situation 5', 3 or 2'. All these three isomers of adenosinemonophosphoric acids meet in the nature. At hydrolysis nucleic acids (see) turn out adenosine-3 '-monophosphorus and adenosine-2' - monophosphorus acids («barmy adenylic acids»).

In a free look adenosine-5 '-monophosphorus to - that, for the first time received by Embden in 1927 from muscles of a rabbit and sometimes called «muscular» adenylic to - that preferential meets:

From various fabrics are allocated also adenosine-2', 3 '-and adenosine-3', 5' - cyclophosphates, i.e. cyclic AMF in which the rest phosphoric to - you form ethers according to hydroxyls at the second and third or third and fifth atoms of the rest of a ribose. Cyclic 3', 5' - AMF plays an important biological role, e.g. performing function of the activator phosphorylases (see) and other enzymes.

Adenozinpolifosforny acids usually are derivatives 5 '-AMF. Fabrics of organisms contain also dezoksiadenozinfosforny acids in which the D-ribose is replaced with D-desoxyribose.

Dezoksiadenozinfosforny acids are present at an organism in a free look, receive them as well at hydrolysis deoxyribonucleic acid (see). In total And. to. are strong acids and in the nature are in a type of salts. And. to. intensively absorb ultraviolet radiation in the area apprx. 260 nanometers, they are strong kompleksoobrazovatel and in the nature often are in a type of complex salt with magnesium. Free And. to., and also their alkaline and alkaline-earth salts easily rastvorima in water. Salts of heavy metals form insoluble residues.


Adenosine — 9 - beta D-ribofuranozil-adenine. Represents compound of adenine and a D-ribose. The last the first carbon atom is attached by a beta glycosidic linkage to the ninth atom of adenine. Pier. the weight 267,24, temperature of melting 229 °, is optically active [a]D = — 60 °. Let's well dissolve in hot water, it is bad in cold. Under the influence of acids it is hydrolyzed on adenine and a ribose. At enzymatic deamination (see) in an organism turns into inosine with the subsequent is more educated uric to - you, being an end product of purine exchange.

Adenosine-5' - monophosphoric acid. Well a rastvorima in hot water. Melts at t of 198 — 200 °C decomposition, [a] D = — 47,5 ° (in 2% caustic soda), at alkaline hydrolysis chips off phosphoric to - that and forms adenosine. At enzymatic or chemical deamination of this connection it is formed inosinic acid (see).

Adenosine-3' - monophosphoric acid. It is formed at alkaline hydrolysis of RNA, melts with decomposition at t ° 208 °, [a]D in water = — 38,5 °. At acid hydrolysis it is split on adenine and a phosphoribose. Unlike adenosine-5' - phosphorus («muscular» adenylic) to - you, are not deaminized by a muscular deaminase adenylic to - you also are not phosphorylated with formation of polyphosphoric derivatives.

Adenosine-2' - monophosphoric acid and adenosine-2', 3-cyclic monophosphoric acid. Are formed at alkaline hydrolysis of RNA and physiological value, apparently, have no.

Adenozinmonofosforny acids are the major component along with other nucleotides nucleic acids (see) also meet both in their structure, and in a free look in all fabrics of live organisms. And. to., being in the beginning of a polynucleotide chain m-RNK, matter for initiation of biosynthesis of proteins (see. Proteins ). Closing balance of an adenozil in acceptor RNA sushchestven for their linkng with ribosomes. As a part of RNA the sequences consisting only of adenylic nucleotides contain, and in cells the polynucleotide consisting only of the remains adenylic to - you is formed. The physiological role of this polynucleotide is still not clear. 5 '-AMF is an important component of adenylic system (see below) and takes part in many biologically important reactions.

Plays a special role adenosine-3', 5 '-cyclophosphate (cyclic AMF).

This nucleotide is a mediator of a number of hormones and participates in regulation of many biochemical reactions in cells. Cyclic 3', 5 '-AMF (tsAMF) is formed in cells under the influence of enzyme of adenylatecyclase. This enzyme catalyzes reaction:

Other enzyme (tsAMF diesterase) carries out splitting of phosphoradio communication of tsAMF at the third carbon atom of the ribozny rest with transformation of tsAMF in 5 - AMF. Many hormones (a glucagon, adrenaline and noradrenaline, prostaglandins, a number of hormones of a hypophysis, etc.) activate adenylatecyclase, carrying out the action by means of the formed tsAMF. So, e.g., tsAMF which is formed at activation of adenylatecyclase of glucagonomas or adrenaline turns an inactive kinase of phosphorylase into an active form. The last carries out reaction phosphorylations (see) inactive phosphorylase b with formation of its active form (phosphorylase and) participating in disintegration glycogen (see). Also participation of tsAMF and in activation of some other enzymes as a mediator of effect of hormones is shown. There are instructions, as in other reactions action of tsAMF consists in activation proteinokinaz. Assume that the same mechanism is the cornerstone of a promoting effect of tsAMF on biosynthesis of proteins, a catabolism of lipids, formation of steroids and permeability of biological membranes. Adenylatecyclase is found hl. obr. in various cellular membranes. In this regard it was suggested that, affecting the ATP complex with calcium in membranes, this enzyme along with formation of tsAMF leads to release of calcium ions which influence a condition of membranes (see. Membranes biological ).

Adenosine diphosphoric acid (adenosinepyrophosphoric acid, adenosinediphosphate, ADF). Represents phosphoanhydride 5 '-AMF. The closing balance phosphoric to - you in ADF is connected to AMF vysokoergichesky communication. It is chipped off from ADF in the course of hydrolysis of 1 N of HCl at 100 ° in 7 min. ADF reversibly turns into ATP and in 5' - AMF, forming together with them the so-called adenylic system playing an important role in a number of processes metabolism and energy (see).

Adenosine triphosphoric acid (adenosinetriphosphate, adenilpirofosforny acid, ATP) it was for the first time received by Lomann in 1929 from muscles of a frog. ATP represents pirofosforny anhydride 5 '-AMF, it is strong tetrabasic acid, easily water soluble. ATP contains two vysokoergichesky rests phosphoric to - you (the corresponding bonds in the drawing are designated by wavy line).

ATP together with other nukleozidtrifosfata is substrate for synthesis of RNA in RNK-polimeraznoy reactions. ATP is universal, high-energy (vysokoergichesky) connection (see. Vysokoergichesky connections , Bio-energetics ). ATP is formed of ADF by phosphorylation due to the energy which is released at oxidation of organic matters. ATP together with ADF and with 5' - AMF form adenylic system. Normal in muscles and in other ATP fabrics makes apprx. 75% of adenylic nucleotides to which share in turn falls apprx. 87% of the general fund of free nucleotides. The energy which is saved up in the form of ATP is used in huge number of various endergonichesky processes, i.e. the demanding energy consumptions. Various forms of motion, including muscular contraction, intracellular transport of ions and other substances, biosynthesis of proteins, nucleic acids, photosynthesis etc. belong to their number. All these reactions are catalyzed by the specific enzymes postponing the rest of orthophosphoric, pyrophosphoric or adenylic acids to other substances. Under the influence of enzymes adenozintrifosfataz (see) ATP chips off the rest phosphoric or pyrophosphoric to - you. With participation of ATP in which the rest orthophosphoric to - you is moved it is possible to give formation of glyukozo-6-phosphate under the influence of a hexokinase in the presence of ions of magnesium as an example of reactions:

In a number of reactions, e.g. at education Z-fosfo-alfa-D-ribozilpirofosfata (FRPF) in the reaction catalyzed by ATP enzyme (D - ribozo-5 - phosphate-pyrophosphotransferase), with ATP transfer a pyrophosphate with release of AMF:

ATP + D - riboao-5-phosphate <-> AMF+FRPF.

At last, the group of reactions is connected with transfer of the rest of AMF and release of a pyrophosphate. Treat these reactions formation of aminoacyladenylates (an intermediate product of protein synthesis):

ATP + amino acid -> aminoacyladenylate + a pyrophosphate

with the participation of enzyme of an aminoatsiladenilatsintetaza, synthesis of the coenzymes containing the remains of AMF as, e.g., nicotinamide adenine dinucleotide (NAD) or a flavinadenindinukleotid (FAD), etc. The remains of adenylic acids are a part of many coenzymes and other biologically important substances among which it is possible to call above-mentioned NAD, FAD, NADF, and also a coenzyme And, adenozilmetionin, adenililsulfat, etc. In fabrics of organisms are found also the adenosinetetraphosphate containing four rests phosphoric to - you, and the adenosinepentaphosphate containing five remains phosphoric to - you. However these connections do not replace ATP, and the biological role them remains not clear.

ATP, AMF, ADF, and also adenosine have the expressed pharmakodinamichesky activity: lower blood pressure, activate muscles of a uterus and other bodies thanks to what they find application at vasospasms, a myocardial dystrophy, muscular dystrophy (see. Adenosine triphosphoric acid , Muscular and adenylic drug ).


Bibliography: Dickson M. and Webb E. Enzymes, the lane with English. M, 1966; Mickelson A. M. Chemistry of nucleosides and nucleotides, the lane with English. M, 1966; Chemistry and biochemistry of nucleic acids, under the editorship of I. V. Zbarskoto and S. S. Debov, L., 1968; Joe t J. - P. a. Ricken-SeTg H. V. Cyclic AMP, Ann. Rev. Blochem., 40, p. 741, 1971, bibllogr.; M a n d with 1 P. Frco nucleotides In animal tissues, Progr. Nucleic Acid. Res., v. 3, p. 299, 1964, bibllogr.; Robison G. A. Butcher R. W. a. Sutherland E. W. Cyclic AMP. Ann. Rev. Biochem., v. 37, p. 149, 1968, bibliogr.

I. B. Zbarsky.

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