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V F Pozdnev

Publications and source records attributed to V F Pozdnev.

At least 37 records · Page 2Linked to original sources
PubMed1991

[A fluorometric method of determining cholesterol esterase activity].

A simple and highly specific method for estimating the cholesterol esterase activity is suggested. Cholesterol esterase (EC 3.1.1.13) is incubated with the emulsified substrate, cholesteryl-o-coumarate, at pH 6.6 to yield o-coumaric (trans-2-hydroxycinnamic) acid detected fluorimetrically (lambda exc 363 nm, lambda em 494 nm) at pH 10.4. The fluorescence associated with the unhydrolyzed substrate is negligible. Cholesteryl-o-coumarate is not hydrolyzed by pancreatic lipase, trypsin, or chymotrypsin under the above conditions. About 1 microgram of pancreatic cholesterol esterase can be determined upon 15 min incubation. The substrate was synthesized by condensation of o-acetoxy-trans-cinnamic acid with cholesterol using the di-tert-butyl pyrocarbonate--pyridine--4-dimethylaminopyridine system.

Animals↗
PubMed1991

[New dipeptide fluorogenic substrates of human tissue kallikrein].

Based on 4-methylcoumarinyl-7-amide (Amc) arginine and a series N-alkyloxycarbonyl derivatives of phenylalanine, eleven Amc-derivatives of the type ROCO-Phe-Arg-Amc (R = alkyl) were synthesized; also were n-C3H7OCO-Leu-Arg-Amc and n-C3H7OCO-D-Phe-Arg-Amc synthesized. The enzymatic hydrolysis of these compounds under the action of tissue and plasma human kallikreins were studied. Tissue kallikrein from human urine hydrolyzed the compounds with R = n-propyl and n-butyl and n-C3H7OCO-Leu-Arg-Amc more readily than the known substrates Z-Phe-Arg-Amc and H-Pro-Phe-Arg-Amc. n-C3H7OCO-D-Phe-Arg-Amc is a weak inhibitor of this enzyme (Ki = 1.5.10(-4) M). Human plasma kallikrein hydrolyzed these novel substrates at a lower rate than Z-Phe-Arg-Amc.

Arginine↗
PubMed1990

[A photometric method of determining the activity of antithrombin III using a peptide coumarylamide substrate].

Toz-Gly-Pro-Arg-4-methylcoumaryl-7-amide is recommended for antithrombin-III (AT-III) photometry as a substrate. This substrate is cleaved by thrombin at 366 nm. AT-III photometry with this substrate is in accord with the requirements to methods used in clinical laboratory diagnosis, and the results of such measurement are in good correlation with the data of AT-III analysis with Chromozym-TH substrate. Use of photometry with methylcoumaryl substrates for measuring protease activities is more available than the traditional fluorometry.

Antithrombin III↗
PubMed1990

[The peptidase activity of a cellular extract of the causative agent of plague].

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.

Aminopeptidases↗
PubMed1990

[Role of aminopeptidases in enkephalin catabolism: comparative study of the regional distribution of aminopeptidases and enkephalinase A in the rat brain].

In order to elucidate the role of aminopeptidases in enkephalin catabolism in rat brain, the local distribution of two types of cerebral cellular membrane aminopeptidases (puromycin-sensitive and puromycin-insensitive ones) and of the enkephalin system marker, enkephalinase A, was studied. It was found that the distribution patterns of the former enzymes differ essentially from that of enkephalinase A. Study of coupling between the enzymatic activities in different regions of rat brain revealed a strong correlation between the activities of puromycin-insensitive aminopeptidase and enkephalinase A in midbrain (including hypothalamus). It was supposed that in midbrain the role of aminopeptidase M in intrasynaptic inactivation of enkephalins is much more conspicuous than in other regions of rat brain. The puromycin-sensitive aminopeptidase activity does not seem to play a role in enkephalin catabolism.

Aminopeptidases↗
PubMed1990

[Photometric method of determination of the amidase activity of proteinases using 4-methylcoumaryl-7-amide substrates].

It was shown that 7-amino-4-methylcoumarin (MC-amine), resulted from the enzymatic hydrolysis of 4-methylcoumaryl-7-amide (MC-amide) peptide substrates, may be estimated not only fluorometrically but also photometrically. A photometric method for estimating activity of tissue kallikrein (EC 3.4.21.35) and urokinase (EC 3.4.21.31) is suggested using Z-Phe-Arg-NHMC and Z-Gly-Gly-Arg-NHMC, respectively, as substrates. Kinetic parameters of the enzymatic hydrolysis, as obtained by photometric and fluorometric detection of the MC-amine formed, were in good agreement. The differential coefficient of molar extinction of the substrates and MC-amine at 360 nm was found to be 10,800 M-1 cm-1.

Amino Acid Sequence↗
PubMed1989

[Interaction of placental diamine oxidase with carboxyl-substituted lysine].

The interaction between diamine oxidase (DAO) of human placenta and carboxyl-substituted lysines, including N-terminal lysine containing peptides, occurs at rather a high rate and is characterized by the following features. First, the enzyme catalyzes the oxidative deamination of one amino group in the N-terminal lysine at a rate which is inversely proportional to the peptide length. Second, the bound derivatives induce a noncompetitive reversible inhibition of DAO which is enhanced during their coincubation. The inhibiting capacity of this compound is directly proportional to the peptide length; therefore, the tripeptides with the N-terminal lysine can be effective inhibitors that are not practically deaminated in the presence of DAO. Third, the binding of carboxyl-substituted lysines to DAO as well as the inhibition reaction are reversible processes and, with some limitations, can be used for enzyme purification. An analysis of the total activity of DAO in the placenta before and after fractionation of tissue extracts on molecular sieves showed that part of the enzyme is in a blocked state in vivo which does not exclude the possibility that N-terminal lysine containing peptides are related to natural DAO inhibitors.

Amine Oxidase (Copper-Containing)↗
PubMed1983

[Prolylendopeptidase activity in various animal organs].

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%.

Animals↗
PubMedDate not supplied

Optical biosensor investigation of interactions of biomembrane and water-soluble cytochromes P450 and their redox partners with covalently immobilized phosphatidylethanolamine layers.

A phospholipid-containing biochip was created by covalently immobilizing phospholipids on the optical biosensor's aminosilane cuvette and employed to monitor the interactions of the membrane and water-soluble proteins in cytochrome P450-containing monooxygenase systems with planary layers of dilauroylphosphatidylethanolamine (DLPE) and distearoylphosphatidylethanolamine (DSPE), differing in acyl chain length. It was shown that the full-length membrane proteins-cytochrome P4502B4 (d-2B4), cytochrome b5 (d-b5) and NADPH-cytochrome P450 reductase (d-Fp)-readily incorporated into the phospholipids. The incorporation was largely due to hydrophobic interactions of membranous protein fragments with the phospholipid layer. However, electrostatic forces were also but not always involved in the incorporation process. They promoted d-Fp incorporation but had no effect on d-b5 incorporation. In low ionic strength buffer, no incorporation of these two proteins into the DSPE lipid layer was observable. Incorporation of d-b5 into the DLPE layer was abruptly increased at temperatures exceeding phospholipid phase transition point. Incorporation of d-2B4 was dependent on its aggregation state and decreased with increasing protein aggregability. Water-soluble proteins either would not interact with the phospholipid layer (adrenodoxin) or would bind to the layer at the cost of only electrostatic (albumin) or both electrostatic and hydrophobic (P450cam) interactions.

Biosensing Techniques↗