ARGININE (alpha amino - delta guanidinovalerianovaya acid) — natural amino acid of the main character:
And. melts with decomposition at t ° 238 °, we will easily dissolve in water, it is insoluble in alcohol and ether. Together with lysine (see) and histidine (see). And. belongs to diamino acids which were called before also hexone bases as they contain 6 carbon atoms and have the expressed main properties; Isoelectric point And. lies at pH 10,76. And. easily forms salts with acids, and nitrate, picrate and pikrolonat And. difficult rastvorima, and flavianat and a phosphotungstate are almost insoluble that finds application at allocation And. from hydrolyzates of proteins and other sources. Natural L-arginine rotates the plane of polarization to the right: [a] D = + 48,1 in 5 N of HCl and +21,8 in water at t 25 °. At alkaline hydrolysis, and also under the influence of enzyme arginases (see). And. it is split on urea (see) and amino acid ornithine (see). Contains in all organisms as a part of proteins, and also in a free look — in a blood plasma and other fabrics. Especially there is a lot of And. contains in proteins of the main character — histones (see) and protamins (see) cellular kernels. And. and ornithine play a large role as intermediate products in exchange of nitrogenous substances in a liver (see. Nitrogen metabolism ). In the course of synthesis of urea ornithine attaches ammonia and carbonic acid, forming amino acid as intermediate compound citrulline (see) which is aminated further at the expense of an amino group aspartic acid (see) through a stage arginineamber to - you. From formed And. enzyme the arginase chips off urea again and forms ornithine in a so-called ornitinovy tricarbonic acid cycle (see the Ornitinovy cycle). At enzymatic decarboxylation (see) bacteria from And. strongly alkaline amine — agmatin is formed. And. in an organism reacts transfer of amidinovy group (reaction of a transamidinirovaniye) with formation of other guanidinovy derivatives — glycocyamine (see), creatine (see), etc.
And. speed of his synthesis in an organism does not belong to irreplaceable amino acids for the person, however, especially with an active growth, can be insufficient that results in need of introduction it from the outside (with food). And., thus, is on the verge between replaceable and irreplaceable amino acids.
At the disease known under the name cystinurias (see), with urine along with cystine significant amounts are allocated And., a lysine and ornithine, however the last three amino acids well of a rastvorima, and in a deposit drops out only cystine (see). The cystinuria is caused by inherited disorders general for the called amino acids of the mechanism of active transport and the return absorption And., lysine, ornithine and cystine. With exchange And. also some inherited disorders of activity of enzymes of an ornitinovy cycle of a mochevinoobrazovaniye are connected. So, at inborn insufficiency of an argininosuktsinatsintetaza (K.F.126.96.36.199) the tsitrullinemiya — excess accumulation in blood and fabrics of citrulline takes place. At insufficiency of an argininosuktsinaza (argininosuktsinat-lyase, K.F.188.8.131.52) it collects and allocated with urine arginineamber to - that.
Definition And. in proteins and in fabrics along with definition of other amino acids usually make by methods of a chromatography (see). For specific definition And. and other derivatives of guanidine very sensitive staining reaction of Sakaguchi consisting in development of intensive orange-red coloring with α-naphthol and hypochlorite in alkaline condition is convenient.
See also Amino acids .
Bibliography: Greenstein J. River and. W i n i t z M. Chemistry of the amino acids, v. 1—3, N. Y. — L., 1961.
I. B. Zbarsky