Amino acids (synonym aminocarboxylic acids) — the organic (carboxylic) acids containing one or more amino groups; main structural part of a molecule of proteins.
Depending on the provision of an amino group in a carbon chain in relation to a carboxyl group (i.e. at the carbon atoms second, third etc.) distinguish α-, β-, γ-amino acids etc. Many Amino acids are found in live organisms in a free look or as a part of more difficult connections. It is described apprx. 200 various natural Amino acids among which are especially important apprx. 20, being a part proteins (see). All Amino acids found in proteins represent α-amino acids and answer the general formula: RCH(NH 2 ) COOH, where R — unequal in different And. the radical attached to the second carbon atom of a chain. The amino group also is attached to the same carbon atom. Thus, at this carbon atom of 4 unequal deputies, and it is asymmetric.
Even before discovery of Amino acids as special class of chemical substances the French chemists Voklen and Robike (L. W. Vauquelin, P. J. Robiquet, 1806) isolated the crystal asparagine representing amide from juice of an asparagus aspartic acid (see) and entering as one of And. in composition of proteins.
The first natural amino acid (cystine) was discovered in 1810 in urinary stones by Vollaston (W. N of Wollaston); in 1819 J. L. Proust, conducting experiments on fermentation of cheese, allocated crystals of a leucine. In 1820 Mr. of Brakonno (N. of Braconnot) glycine which had sweet taste received from a hydrolyzate gelatin and it was called glue sugar; only afterwards glycine was carried to And. Brakonno's opening played especially important role as it was the first case of receiving Amino acids from a hydrolyzate of protein; further from hydrolyzates of proteins also the others were allocated and identified And., contained in structure of proteinaceous molecules.
And. have a number of the general properties: these are the colourless, crystal substances melting usually with decomposition at rather high temperatures, sweet, bitterish or fresh on taste. Amino acids are ampholytes, i.e. form salts both with acids, and with the bases and have the nek-ry properties characteristic both for organic acids and for amines. Natural α-amino acids can rotate the plane of polarization in different degree to the right or to the left depending on the nature And. and conditions of the environment, but all of them belong to a L-row, i.e. have an identical configuration of α-carbon atom and can be considered as derivatives of L-alanine or, respectively, L-glitserpnovogo of aldehyde. A variety of properties and character of radicals of various Amino acids defines variety and specific properties as separate And., and proteinaceous molecules which part they are. Chemical constitution and the major properties natural And., the proteins which are found in gpdrolizata, are provided in tab. 1.
- 1 Electrochemical properties
- 2 Optical properties
- 3 Classification of amino acids
- 4 Receiving amino acids
- 5 Definition of amino acids
- 6 Active transport of amino acids
- 7 A role of amino acids in food
- 8 Pathology of exchange of amino acids
- 9 Use of amino acids
- 10 Histochemical methods of identification of amino acids in fabrics
- 11 From Additional materials
- 12 Bibliography
Having amphoteric properties (see. Ampholytes ), And. in solutions dissociate as as acid dissociation (giving a hydrogen ion and being loaded at the same time it is negative), and as basic dissociation (attaching the N-ion and releasing an ion of a hydroxyl), gaining at the same time positive charge. In acid medium basic dissociation amplifies And. also there is a formation of salts to anions of acids. In alkaline condition, on the contrary, And. behave as anions, forming salts with the bases. It is established that Amino acids in solutions almost completely dissociate and are in a type of the amphoteric (bipolar) ions called also by zwitterions or amfiiona:
In acid medium the amphoteric ion attaches the hydrogen ion suppressing acid dissociation and turns into a cation; in alkaline condition with accession of an ion of a hydroxyl basic dissociation is suppressed, and the bipolar ion becomes anion. At a certain value rn Wednesdays, unequal for different And., extent of acid and basic dissociation for this And. it is equalized, and in electric field And. does not move neither to the cathode, nor to the anode. This value rn is called an isoelectric point (pI), edges of subjects are lower, than it is more at this And. acid properties are expressed, and that is higher, than at And. the main properties are more expressed (see. Isoelectric point ). At pI solubility And. becomes minimum according to what it is easier to besiege it from solution.
All α-amino acids, behind an exception glycine (see), have asymmetric carbon atom. Such atom always is the 2nd, or α-carbon, atom, all four valencies to-rogo are occupied by various groups. In this case two stereoisomeric forms which are specular reflection of each other and incompatible among themselves like the right and left hand are possible. On the scheme two stereoisomers A are represented. alanine in the form of the volume image and the projection to the planes corresponding to it. The image is conditionally considered to be the left configuration (L), at the left on the right — the right configuration (D). Such configurations correspond to left-and dextrorotatory glyceraldehyde which is taken for mother compound during the definition of a configuration of molecules. It is shown that all natural And., received from hydrolyzates of proteins, on a configuration of α-carbon atom correspond to a L-row, i.e. can be considered as derivatives of L-alanine, in Krom one hydrogen atom in metalny group is replaced with more compound radical. Specific rotation of the plane of polarization of light of separate Amino acids depends as on properties of all molecule in general, and rn-solution, temperature and other factors.
Specific rotation of the major And., their isoelectric points and indicators of constants of acid dissociation (rk and ) are presented in tab. 2.
Earlier optical antipodes of L-amino acids, i.e. amino acids of a D-row, called «not natural», however in a crust, time of amino acid of a D-row are found as a part of some bacterial products and antibiotics. So, capsules of sporiferous bacteria (you. subtilis, V. anthracis, etc.) considerably consist of the polypeptide constructed of the remains D-glutaminic to - you. D-alanine and D-glutamidovaya to - that are a part of the mukopeptid forming cell walls of a number of bacteria; valine, phenylalanine, ornithine and a leucine of a D-row contain in composition of gramicidins and many other peptides — antibiotics, etc. Stereoisomeric And. significantly differ on the biological properties, they are attacked by the enzymes specific only to a certain optical configuration, do not replace or only partially replace each other in a metabolism, etc. D-isomers alanine (see), leucine (see), serine (see), tryptophane (see) and valine (see) very sweet whereas L-stereoizomery of alanine and serine moderately sweet, tryptophane — are tasteless, and a leucine and valine — are bitterish. Characteristic «meat» taste L-glutaminic to - you are absent at a D-form. Synthetic And. usually represent racemates, i.e. mix of equal quantities D-and L-forms. They are designated as DL amino acids. By means of some special reactants or processing by some enzymes synthetic And. it is possible to divide into D-and L-forms or to receive only one desirable stereoisomer.
Classification of amino acids
Characteristic properties of separate Amino acids are defined by a side chain, i.e. the radical standing at α-carbon atom. Depending on a structure of this radical A. subdivide on aliphatic (the majority concerns to them And.), aromatic (phenylalanine and tyrosine), heterocyclic (histidine and tryptophane) and imino-acids (see) which have a nitrogen atom standing at α-carbon atom it is connected to a side chain in a pirrolidinovy ring; proline and oxyproline concern to them (see. Prolin ).
On number of carboxyl and amine groups A. divide as follows.
Monoamino monocarboxylic amino acids support one carboxyl and one amine groups; the most part concerns to them And. (their pI lies apprx. rn 6).
Monoamino dicarboxylic amino acids contain two carboxyl and one amine groups. Asparaginic and glutamic acid (see) have subacidic properties.
On chemical composition of substituting groups distinguish: hydroxy-amino acids (contain spirit group) — serine and threonine (see), sulfur-containing And. (contain sulfur atoms in the structure) — cysteine, cystine (see) and methionine (see); amides (see) dicarbonic And. — asparagine (see) and glutamine (see), etc. Amino acids with the hydrocarbon radical, e.g. alanine, a leucine, valine, etc., give to proteins hydrophobic properties; if the radical contains hydrophilic groups as, e.g., at dicarbonic And., they report to protein hydrophily.
In addition to already mentioned And. (see the tab. and the relevant articles), in tissues of the person, animals, plants and at microorganisms even more than 100 are found And., many of which play an important role in live organisms. So, ornithine and citrulline (belong to diaminocarboxylic And.) play an important role in a metabolism, in particular in synthesis of urea at animals (see Arginine, Urea). The highest analogs glutaminic to - you are found in organisms: α-aminoadipinic to - that with carbon atoms and α-aminopimelic to - that with 7 carbon atoms. As a part of collagen and gelatin oxylysine is found:
having two asymmetric carbon atoms. From aliphatic monoamino monocarboxylic And. meet α-aminobutyric to - that to - that to - that, norvalin (α-aminovalerian to - that) and norleucine (α-ampnokapronovy to - that). The last two are received synthetic, but do not meet as a part of proteins. Homoserine (α-amino-γ-oksimaslyany to - that) is the highest analog of serine. Respectively α-amino-γ-tiomaslyany to - that, or gomotsistein, is a similar analog of cysteine. Two last And. along with lantioniny:
take part in exchange sulfur-containing And. 2,4 Dioxyphenylalanine (DOFA) are an intermediate product of exchange phenylalanine (see) and tyrosine (see). Of tyrosine it is formed such And., as 3,5 diiodotyrosine — an intermediate product of education thyroxine (see). In a stand-at-ease and as a part of some natural substances meet And., metilirovanny (see. Methylation ) on nitrogen: methylglycine, or methyl-aminoacetic acid [CH 2 (NHCH 3 ) COOH], and also methylhistidine, abrin, methyllysine. The last is recently found as a part of nuclear proteins — histones (see). Also acetylized derivatives are described And., including atsetillizin structure of histones.
In addition to α-amino acids in the nature, hl. obr. in a free look and as a part of some biologically important peptides, meet Amino acids, containing an amino group at other carbon atoms. Treat them β-alanine (see. Alanin ), γ-aminobutyric to - that to - that to - that (((see. Aminobutyric acids ), playing an important role in functioning of a nervous system, δ-aminolevulinic to - that to - that to - that, being an intermediate product of synthesis of porphyrines. K A. carry also taurine (H 2 N — CH 2 — CH 2 — SO 3 H), formed in an organism in the course of exchange of cysteine.
Receiving amino acids
And. receive by various methods, some of them are intended especially for receiving these or those A. Naiboley by widespread general methods of chemical synthesis And. the following is.
1. Amination of halide derivative organic acids. On halide derivative (usually bromzameshchenny acid) work with ammonia therefore haloid is replaced on an amino group.
2. Receiving And. from aldehydes by processing by their ammonia and hydrogen cyanide or cyanides. As a result of such processing cyan alcohol which is aminated further, forming an aminonitrile turns out; saponification of the last gives And.
3. Condensation of aldehydes with derivatives of glycine with the subsequent recovery and hydrolysis.
Separate And. can be received from hydrolyzates of proteins in the form of almost insoluble salts or other derivatives. E.g., cystine and tyrosine are easily besieged in from electric to a point; diamino acids besiege in the form of salts phosphatotungstic, picric (lysine), flavpanovy (arginine) and other acids; dicarbonic And. besiege in the form of calcic or baric salts, glutaminic to - that is allocated in the form of a hydrochloride in acid medium, asparaginic to - that is in the form of copper salt etc. For preparative allocation of a row A. from hydrolyzates of protein apply also methods of a chromatography and an electrophoresis. For the industrial purposes many And. receive by methods of microbiological synthesis, allocating them from culture medium of certain strains of bacteria.
Definition of amino acids
as the general reaction on And. most often apply staining reaction with ningidripy (see) which during the heating gives with different And. violet coloring of various shades. Apply also Folin's reactant (1,2-naphthoquinone-4-sulfoiovo-acid sodium), deamination nitrogenous to - that with gas-metric definition of the emitted nitrogen according to Van-Slayka (see. Van-Slayka methods ).
Definition separate And., and also amino-acid composition of proteins and free And. blood and other liquids and body tissues usually make by methods of paper chromatography or on ion-exchange resins (see. Chromatography ) or electrophoresis (see). These methods allow to determine qualitatively and quantitatively trace amounts (a share of milligram) of any Ampere-second by use of standard samples of these connections as «witnesses» or standards. Usually use autoanalyzers A. (see. Avtoanalizatora ), carrying out the integrated amino-acid analysis of the samples containing only several milligrams in several hours And. By even more bystry and sensitive method of definition And. the gas chromatography of their flying derivatives is.
And., coming to a human body and animals with food, hl. obr. in the form of food protein, take the central place in nitrogen metabolism (see) also provide synthesis in an organism of its own proteins and nucleic acids, enzymes, many coenzymes, hormones and other biologically important substances; in plants from And. are formed alkaloids (see).
In blood of the person and animals the fixed level of contents normal is supported And. in a free look and as a part of small peptides. The blood plasma of the person on average contains 5 — 6 mg of nitrogen A. (usually called by amino nitrogen) on 100 ml of plasma (see. residual nitrogen ). In erythrocytes the content of amino nitrogen in 11/2 — 2 times are higher, in cells of bodies and fabrics it is even higher. In days with urine it is allocated apprx. 1 g And. (tab. 3). At plentiful and unbalanced proteinaceous food, at a renal failure, a liver and other bodies, and also at some poisonings and inherited disorders of exchange And. contents them in blood increases (hyper aminoacidemia) and with urine noticeable quantities are distinguished And. (see. Aminoatsiduriya ).
Active transport of amino acids
the Essential role in exchange And. plays active transport And. against a gradient of concentration. This mechanism maintains concentration And. in cells on more high level, than their concentration in blood, and also regulates absorption And. from intestines (in the course of digestion of proteinaceous food) and the return absorption them from renal tubules after filtering of urine in malpigiyevy balls. Active transport And. it is connected with action of the specific proteinaceous factors (permeaz and translocases) which are selectively connecting And. and the high-energy connections which are carrying out their active transfer due to disintegration. Mutual competition of one And. among themselves for active transfer and absence it at others And. shows that there are several systems of active transport And. — for separate groups A. So, cystine, arginine, a lysine and ornithine possess the general system of transport and compete among themselves in this process. Other system of transport provides transfer through membranes of glycine, proline and oxyproline and, at last, the third system, apparently, is the general for big group of the others And.
A role of amino acids in food
the Person and animals use the nitrogen arriving with food in a look in a metabolism And., hl. obr. as a part of proteins, some other organic compounds of nitrogen, and also ammonium salts. From this nitrogen by processes of amination and transamination (see. Interamination ) in an organism are formed various by A. Nekotorye A. these lives cannot be synthesized in an animal organism, and for maintenance And. shall come surely to an organism with food. Such And. call irreplaceable. Irreplaceable And. for the person: tryptophane (see), phenylalanine (see), lysine (see), threonine (see), valine (see), leucine (see), methionine (see) and isoleucine (see). The others And. carry to replaceable, but some of them are replaceable only conditionally. So, tyrosine is formed in an organism only of a fenilalashga and at arrival of the last in insufficient quantity it can be irreplaceable. Like it cysteine and cystine can be formed of methionine, but are necessary at a lack of this A. Arginin is synthesized in an organism, but the speed of its synthesis can be insufficient at the increased requirement (especially with an active juvenile growth). Requirement in irreplaceable And. it was studied in researches on nitrogen equilibrium, proteinaceous starvation, the accounting of the consumed food, etc. Nevertheless the need for them does not give in to the exact account and can be estimated only approximately. Data about recommended and certainly irreplaceable A. Potrebnost' number, sufficient for the person, in irreplaceable are provided in tab. 4 And. increases during the periods of intensive growth of an organism, at the increased disintegration of proteins at some diseases.
Accessory And. to replaceable or irreplaceable to various organisms it is not absolutely identical. So, e.g., the arginine and a histidine relating to replaceable And. for the person, are irreplaceable for hens, and a histidine also for rats and mice. Autotrophic organisms (see), to the Crimea plants and many bacteria belong, are capable to synthesize all necessary for A. Odnako a number of bacteria needs available these or those And. in culture medium. The types or strains of bacteria which are selectively needing available certain are known And. Such mutant strains, which growth is provided only at addition on Wednesday certain And., call auksotrofny (see. Auksotrofny microorganisms ). Auksotrofny strains grow on the Wednesday, full in other relations, with a speed proportional to quantity added irreplaceable And., therefore they are applied sometimes to microbiological determination of content this And. in these or those biological materials, e.g. Guthrie method (see).
A lack of food of one of irreplaceable And. leads to a growth disorder and the general dystrophy, but lack of some And. can give also specific symptoms. So, the lack of tryptophane quite often gives the iyellagropodobny phenomena as of tryptophane in an organism it is formed nicotinic to - that (at experimental rats at a lack of tryptophane opacification of a cornea, a cataract, loss of wool, anemia is observed); the lack of methionine leads to damage of a liver and kidneys; the lack of valine causes neurologic symptoms etc.
Good nutrition is provided at the balanced contents separate And. in food. Surplus of some And. it is also adverse. Excess of tryptophane leads to accumulation of a product of its exchange — 3-oxyanthranilic to - you, edges can cause tumors of a bladder. At unbalanced food excess of some amino acids can break exchange or use of others And. and to cause insufficiency of the last.
Pathology of exchange of amino acids
the Most frequent reason of amnnoatsiduriya and hyper aminoacidemias are the diseases of kidneys connected with disturbance of allocation and the return absorption A. Ryad of specific disturbances of exchange And. it is connected with hereditary insufficiency of the certain enzymes participating in their metabolism.
So, rare, but long ago the known disease - an alkaptonuria is caused by insufficiency in an organism of enzyme — oxidases homogentistic to - you (one of products of an intermediate metabolism of tyrosine). At an alkaptonuria of a gomogentpza new to - that is allocated with urine and, being oxidized on air, paints it in black color. Though the alkaptonuria is found since childhood, clinical disturbances at the same time are insignificant and come down only to bigger exposure to a special type of an arthropathy (ochronosis). Other inherited disorder of exchange And. the fenilketonuriya is. At this disease insufficiency or lack of enzyme of a phenylalanine-4-hydroxylase takes place owing to what transformation of phenylalanine into tyrosine is broken; the tyrosine which normal is not irreplaceable And., at patients with a fenilketonuriya becomes irreplaceable as it cannot be formed of phenylalanine. Fenilketonuriya is connected with heavy clinical disturbances from which the most important is disturbance of development of a brain and thereof the heavy mental retardation which is shown since the early childhood. Excess accumulation of phenylalanine in blood (giperfenilalaninemiya) and in urine, in particular accumulation of products of its exchange is the reason of these disturbances, in particular phenyl-pyruvic to - you are (fenilketonuriya) from which there is a name of this disease. In a crust, time development of the neurologic disturbances caused by a fenilketonuriya is successfully softened, appointing babies a special diet with very low content of phenylalanine. Some major inherited disorders of exchange of amino acids are presented in tab. 5.
A specific place is held by sharply expressed aminoacidurias (see), the resulting disturbances of transport And. and, respectively, their absorption from renal tubules and from intestines. The cystinuria diagnosed on allocation with urine of cystine and to its adjournment in the form of stones and rainfall in uric ways belongs to such disturbances. Actually the cystinuria is connected with disturbance of the general system of active transport of four And. — lysine, arginine, ornithine and cystine. At a cystinuria it is allocated on average these more than 4 g And. in days from which only apprx. 0,75 g falls to the share of cystine however cystine owing to the low solubility drops out at the same time in a deposit and causes adjournment of stones. Disturbance of other system of active transport, the general for glycine, proline and oxyproline, leads to the increased allocation with urine of these three And. (without emergence of signs of clinical disturbances). At last, disturbance of one more general system of transport And., to the Crimea the big group of all others belongs, apparently, And., called by Hartnup's disease, it is connected with the diverse clinical manifestations unequal in different cases.
Use of amino acids
And. find broad application in medicine and other areas. Various sets A. and the hydrolyzates of proteins enriched separate And., are applied to parenteral food at operations, diseases of intestines and disturbances of absorption. Some And. render specific therapeutic effect at various frustration. So, methionine is applied at obesity of a liver, cirrhoses, etc.; glutaminic and γ-amino-maslyany acids give good effect at some diseases of c. N of page (epilepsy, reactive states etc.); the histidine is applied sometimes to treatment of patients with hepatitises, a peptic ulcer of a stomach and a duodenum.
And. apply also as additives to foodstuff. Additives of a lysine, tryptophane and methionine to foodstuff, defective on the content of these amino acids are almost most important. Additive glutaminic to - you and its salts to a number of products impacts them pleasant meat relish that is often used in cookery. In addition to food of the person and use And. in the food industry, they are used for feeding of animals, for preparation of culture mediums in the microbiological industry and as reactants.
Histochemical methods of identification of amino acids in fabrics
Reactions of identification And. in fabrics hl are based. obr. on identification of amino groups (NH 2 -), carboxyl (SOON —), sulphhydryl (SH-) and disulfide (SS-) groups. Methods of identification separate are developed And. (tyrosine, tryptophane, histidine, arginine). Identification And. it is carried out also by means of blocking of these or those groups. It must be kept in mind what gistokhimik deals, as a rule, with the denatured protein therefore results of histochemical methods are not always comparable to biochemical.
For identification of SH-and SS-group of the best reaction with 2,2 ?-dioksi - 6,6 ′ - dinaftildisulfidy (DDD), based on education naphthyl a disulfide and, connected with the protein containing SH groups is considered. For development of coloring drug is processed diazonium salt (solid blue B or strong black To), edges connects with naftildisulfidy, forming the azoic dye painting sites of localization SH-and SS-group in fabrics in shades from pink to blue-violet. The method allows to carry out quantitative comparisons. Fabric is fixed in liquid Carnoy, Buena, in formalin. The best results are yielded by 24-hour fixing in 1% solution trichloroacetic to - you for 80% alcohol with after-flush in a series of alcohols of the increasing concentration (80, 90, 96%), then dehydration and paraffin embedding is made. Reactants are necessary for reaction: DDD, diazonium salt, 0,1 M veronal - acetate buffered solution (rn 8,5), 0,1 M phosphatic buffered solution (rn 7,4), alcohol, sulphuric ether.
α-amino acids come to light with the help Schiff's ninhydrin reactant. The method is based on interaction of ninhydrin with amino groups (NH 2 -); the aldehyde which is formed at the same time comes to light Schiff's reactant. Material is fixed in formalin, anhydrous alcohol, Tsenker's liquid, consists in paraffin. Reactants are necessary: ninhydrin, Schiff's reactant, alcohol. The fabrics containing α-amino groups, are painted in pinkish and crimson shades. Specificity of reaction, however, is disputable, t. to oxidation by ninhydrin not only α-amino acids, but also other aliphatic amines can be exposed.
Tyrosine, tryptophane, a histidine come to light by a tetrazoniyevy method. Diazonium salts in alkaline condition are in a type of the diazonium hydroxides joining the called amino acids. For strengthening of color coloring cuts process β-naphthol or N-acid. Fixing by formalin, liquid Carnoy. Necessary reactants: tetrazotirovanny benzidine or is better solid blue B, 0,1 M veronalatsetatny buffered solution (rn 9,2); 0,1 N of HCl, N-acid or β-naphthol. Depending on a reactant cuts are painted in violet-blue or brown color. At assessment of results it must be kept in mind a possibility of accession to diazonium hydroxide of phenol and arylamines. Apply control reactions to a differentiation of amino acids.
From Additional materials
During the writing of the sequence of the amino-acid remains in a polypeptide chain the International union of theoretical and applied chemistry and the International biochemical union suggested to use the reduced names A., consisting usually of the first three letters of the full name of the corresponding amino acid (see the table). Use of international latinizirovanny standard system of symbols and reductions represents big advantages from the point of view of collecting, processing and search of scientific information, elimination of mistakes at transfer of texts from foreign languages, etc. The unified reduced names of chemical connections, including and amino acids, are especially important not only in the international relation, but also for use in the USSR where scientific literature is published in tens of languages, various alphabetically, to lexicon and a tracing of special terms and their reduced designations.
The reduced designations free And. it is not necessary to use in the text of works, it is admissible only in tables, lists, schemes.
Where the sequence of the amino-acid remains in a peptide chain is known, symbols of the remains write one after another, connecting them hyphens; that chain or a part of a chain where the sequence of connection of the amino-acid remains is unknown, consists in parentheses, and symbols of the remains And. are divided by commas. During the writing of linear peptides or proteins on the left end of the established sequence (i.e. on its N-end) the symbol of the amino acid bearing a free amino group, and on the right end (on the C-end) — a symbol of the rest of amino acid bearing a free carboxyl group is put. It is more preferable to represent a polypeptide chain horizontally, but not vertically located sequence. Symbols And. designate natural (L-) forms, their antipodes — a D-symbol, to-ry put just before a symbol of amino acid, without separating from it a hyphen (e.g., Ley-Dfen-Gli).
Symbols less widespread in wildlife And. especially make a reservation in each publication. It is recommended to observe only the following principles, e.g., of hydroxyamino acid (hydroxy-amino acid): hydroxylysine (oxylysine) — Hyl (Olya) etc.; hallo - amino acids: hallo - from a leucine — aile (ail), hallo - oxylysine — aHyl (aol); noraminokislota: norvalin — Nva (Nva), norleucine — Nle (Nle) etc.
Table. The reduced writing of symbols of amino acids, the most widespread in wildlife
Braunstein A. E. Biokhimiya of amino-acid exchange, M., 1949, bibliogr.; Maister A. Biokhimiya of amino acids, the lane with English, M., 1961; Greenstein J. P. a. Winitz M. Chemistry of the amino acids, v. 1—3, N. Y. — L., 1961; Meister A. Biochemistry of the amino acids, v. 1—2, N. Y., 1965; Nivard R. J. E. and. Tesser G. I. Amino acids and related compounds, Comprehens. Biochem., v. 6, p. 143, 1965, bibliogr.; The nomenclature of biological chemistry, the lane with English, under the editorship of A. E. Braunstein, century 1, page 13, etc., M., 1968.
Histochemical methods of identification of Amino acids in fabrics
Lillie R. Patogistologicheskaya of the technician and a practical histochemistry, the lane with English, M., 1969, bibliogr.; Pearce E. A histochemistry, the lane with English, page 73, M., 1962; The Principles and methods of the gistotsitokhimichesky analysis and pathology, under the editorship of A. P. Avtsyn, etc., L., 1971, bibliogr.
I. B. Zbarsky; R. A. Simakova (gist.), N. G. Budkovskaya.