Biomedical subjects
Publications and source records attributed to L P Alekseenko.
Peptidase activity of Yersinia pestis cell extract was studied by the hydrolysis of synthetic and some natural substrates, as well as the hydrolysis of fluorogenic aminopeptidase substrates. All peptides and fluorogenic substrates under test were split by Y. pestis cell extract, the splitting of alanylaminopeptidase substrate being linked with at least two enzymes of this cell extract.
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The paper is concerned with the action of 1200-fold purified prolylendopeptidase II (PE-E) from human erythrocytes and the action of highly purified prolyl-D-L-alanine peptidyl hydrolase (PE-A) from bovine adenohypophysis on teprotide (BPP9a, SQ 20881), a nonapeptide from venom of the snake Bothrops Jararaca--an inhibitor of peptidyl dipeptidase A (carboxycathepsin). Both the purified preparation PE-E and highly purified preparation PE-A split teprotide at the bonds Pro3-Arg4 and Pro5-Gln6. The Pro8-Pro9-OH bond was not split by the two enzymes. The comparative characteristics of the properties of PE-E and PE-A are presented and the possible physiological role of these enzymes is discussed.
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The paper is concerned with the distribution of prolylendopeptidase activity as measured by the hydrolysis of Z-Gly-Pro-pNA in extracts of various cattle tissues (hypophysis, liver, kidneys, heart, skeletal muscle, lungs, spleen, testicles, pancreas, thyroid, brain, small intestine, blood plasma). The highest specific activity was seen in the cerebral cortex, the lowest, in the spleen. The molecular weights of proteins with prolylendopeptidase activity in the extracts of the adenohypophysis, liver, kidneys, skeletal muscle and spleen were determined by gel filtration in an Ultrogel AcA 44 column, and the values of 57 000-66 000 dalton were obtained. Studies of the action of various inhibitors showed that complete inhibition of activity by PCMB (1 X 10(-3) M) was attained only in adenohypophyseal extracts, whereas in those of the spleen, skeletal muscle and liver, the inhibition reached 85%. The activity in the kidneys was inhibited by 65%.
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Apart from the generally known functions, the heart has also an endocrine function. Atrial cardiocytes, being typical secretory cells, release peptide hormones into the blood stream: atrial natriuretic peptide containing 28 amino acids and cardiodilatin. The structure of atrial peptides was determined. It was shown that both peptides were derived from their common precursor, a protein containing 151 amino acids. The presence of specific receptors is demonstrated on plasmatic membranes of cells of kidney epithelium, arterial smooth muscle, arterial endothelium, kidney cortex and hypophysis. The interaction of atrial peptides with these receptors activates the guanylate cyclase system. The biological action of atrial peptides manifests itself in the quick, massive and instantaneous increase of diuresis and electrolyte excretion, elevated clearance of creatinine, decrease of kidney vascular resistance, intensification of glomerular filtration, inhibition of stimulated secretion of aldosterone, relaxation of blood vessels, elimination of arterial and intestinal spasm induced by various endogenous and exogenous vasoconstrictors and in correction of kidney hypertension. Various radioimmunoassays for the presence of atrial peptides in human plasma were developed; it was shown that in patients with congestive heart failure the content of atrial peptides is increased.
Besides generally known functions, the heart has also an endocrine function. Atrial cardiocytes, being typical secretory cells, released peptide hormones into the blood stream: atrial natriuretic peptide containing 28 amino acids and cardiodiolatin. The structure of atrial peptides was determined. It was shown that both derived from their common precursor, a protein containing 151 amino acid. The presence of specific receptors was demonstrated on plasmatic membranes of cells of kidney epithelium, arterial smooth muscle, arterial endothelium, kidney cortex and hypophysis. The interaction of atrial peptides with these receptors activated the guanylate cyclase system. The biological action of atrial peptides manifested itself in the quick, massive and instantaneous increase of diuresis and electrolyte excretion, elevation of clearance of creatinine, decrease of kidney vascular resistance, intensification of glomerular filtration, inhibition of stimulated secretion of aldosterone, relaxation of blood vessels, elimination of arterial and intestinal spasm induced by various endogenous and exogenous vasoconstrictors and correction of kidney hypertension. Various radioimmunoassays for detection of atrial peptides in human blood plasma were developed; it was shown that in patients with congestive failure the atrial peptide content was increased.
A highly sensitive fluorometric method for determination of prolylendopeptidase (PE) activity in human erythrocyte hemolysates in the presence of hemoglobin has been developed. The method is based on measurement of fluorescence of 4-methyl-7-aminocoumarine released in the course of enzymatic reaction from the substrate Z-glycyl-proline-4-methylcoumarine-7-amide. A correlation was introduced for the quenching of fluorescence by hemoglobin. The method is suitable for the determination of PE activity in human erythrocyte hemolysates in various pathological states. The dependence of PE activity on the incubation time, protein and substrate concentrations were studied using the 1,200-fold purified preparations of prolylendopeptidase II. The values of PE activity in erythrocyte hemolysates of healthy donors and in those of patients with odontogenic phlegmons of maxillary-facial area were virtually identical. PE activity in erythrocyte hemolysates of stored blood was 5 times lower than that in the cell hydrolysates of fresh blood. The PE activity was not observed in blood serum of fresh and stored blood of healthy persons and of patients with acute inflammatory processes of maxillary-facial area, as well as in blood serum of patients with hepatitis and glomerulopephritis.