[Methodologic aspects of research on amidation of protein molecules].

The paper deals with methodical aspects of protein amidation study. Critical review of some methodical procedures described in literature has been made. Presence of catalytic activity in medical drugs of serum albumin, human gamma-globulin--as well as in commercial drugs of bovine serum albumin have been detected by means of amino acid analysis (automatic analyzer of amino acids AAA-339T).

[Changes in the proteolytic activity of tissues during aging].

The intensity of proteolytic processes and qualitative composition of autolysis products of the brain, liver and testicle tissues of young and old rats were studied. The gel-chromatographic analysis (Sephadex G-15 and G-50) revealed no considerable amount of high-molecular peptides (1500 Da and over) before and after autolysis. The measurement of the quantity of free amino groups in the gel-chromatographic fraction after the complete acid hydrolysis has confirmed that result.

[Changes in various biochemical and physico-chemical properties of hemoglobin during its aging].

It is shown that hemoglobin senescence leads to both a decrease of amide groups in it and redistribution of the radioactive label (55Fe) in electrophoretic fractions. It is supposed that an increase of the radio-active label in highly mobile hemoglobin fractions of the "old" erythrocytes by 78 and 43% as compared to that of the "young" erythrocytes is related to the deamidation-mediate growth of the negative charge of this protein molecule or partial denaturation of its quaternary structure. The resistance of hemoglobin of the "old" erythrocytes is shown to decrease to acid tissue proteinases of the lysosomal fraction as against hemoglobin of the "young" erythrocytes.

[Degradation of deamidated proteins by tissue proteinases].

The rate of native and deamidized serum albumin in vitro splitting by the brain, liver, kidney, testicle and spleen tissue proteinases was studied at pH 3.2, 4.8, 7.