SERINE — the amino acid relating to hydroxy-amino acids is capable to be synthesized in an organism of animals and the person. Pathology of exchange of S. in an organism conducts to a heavy renal failure. Activity of the nek-ry enzymes participating in S.'s exchange is additional diagnostic test at a number of diseases of a musculoskeletal system.
S.'s rest in a polypeptide chain proteins (see) it is capable to react nucleophilic substitution, leading to formation of covalent intermediate compound. Thanks to this S. is a part of an active center of so-called serinovy enzymes (see). The group of serinovy proteinases is known, e.g., (see. Peptide-hydrolase ), to a cut belong trypsin (see), chymotrypsin (see), thrombin (see), elastase (see), subtilizin. S.'s rest is found also in an active center of acetylcholinesterase (see. Cholinesterases ), an alkaline phosphatase (see. Phosphatases ) and phosphoglucomutases. In the majority phosphoproteins (see) phosphoric to - that joins protein through IT - group of one of the remains of serine. As a part of nek-ry physiologically active peptides serine is also found. AKTG also belongs to such peptides (see. Adrenocorticotropic hormone ). The page is a part not only proteins and peptides (see), but also lipids (see), napr, phosphatidylserine, to-ry can turn into phosphatidylethanolamine and phosphatidylsincaline, etc. S. is necessary also for synthesis of sphingosine — the amino alcohol entering in sphingolipids (see), to-rye along with phosphatides (see) make the ground mass of lipids of a brain. Except, that, sphingolipids are the main component of a myelin cover of nerves.
The page represents white crystal matter, crystals to-rogo have the form of hexagonal plates or prisms, we will well dissolve S. in water, t°pl 223 — 228 ° (with decomposition).
Page — an important intermediate link in a chain of interconversions methionine (see) and cysteine (see), he is the main source of the one-carbon remains used in biosynthetic processes and participates in synthesis glycine (see) and sincaline (see). For page it is necessary for synthesis tryptophane (see) at triptofansinteziruyushchy organisms.
The metabolic chain of S. begins with 3-phosphoglyceric to - you, edges is dehydrogenated to 3 phosphooxypyruvates, and then later transaminations (see) turns into 3 phosphoserine. The final stage of synthesis of S. is hydrolysis 3 phosphoserines under the influence of phosphoserinephosphatase (KF 188.8.131.52).
Serves as the main way of a catabolism of S. it deamination (see) with formation of pyruvate and ammonia, however S. can be exposed to disintegration on the way including trances-nirovaniye with formation of hydroxybutyrate, to-ry further can be recovered in D-glitserat, and then in Z-phosphoglycerate.
Among the diseases connected with disturbance of exchange of S. rare metabolic defect — primary hyperoxaluria like II called by also L-glyceric aciduria is known (see. Oksaloz ). The disease is characterized by education in fabrics of crystals of calcium oxalate and is followed by a heavy renal failure. Believe that this disease is connected with disturbance of catabolic disintegration of S. through a transaminnrovaniye with formation of hydroxybutyrate. Biochemical defect consists, apparently, in loss of ability to recovery of oxypyruvate to D - gli-tserata. In this case with the help lactate dehydrogenases (see) pyruvate it is recovered to L - glitserino-howl to - you, edges in large numbers it is removed with urine. The excess obra*-zovaniye of oxalate from a glioksilat is an indirect consequence of disturbance of metabolism of pyruvate.
Among the enzymes containing S.'s rest in an active center in the diagnostic relation the alkaline phosphatase is especially interesting. Its activity in blood serum considerably increases at nek-ry diseases of bones; decrease of the activity of an alkaline phosphatase can serve as criterion of treatment rickets (see).
Apply to S.'s identification usually chromatography (see) on paper with the subsequent coloring of a hromatogramma ninhydrin. For S.'s allocation from hydrolyzates of proteins use also a column chromatography and ion-exchange chromatography.
See also Amino acids .
Bibliography: Deveni T. and e r-e y I. Amino acids, peptides and proteins, the lane with English, M., 1976; Lenindzhera. Biochemistry, the lane with English, page 24 and other. M, 1976: M e p l e r D. E. Biochemistry, the lane with English, t. 3, page 118, etc., M., 1980.
O. D. Lopina.