Biomedical subjects

L Ia Bessmertnaia

Publications and source records attributed to L Ia Bessmertnaia.

4 recordsLinked to original sources

PubMed1984

[Proteases of swine small intestine enterocytes. Kinetics of substrate hydrolysis and inhibition of aminopeptidase N from brush border vesicles].

The kinetics of hydrolysis of L-leucine p-nitroanilide and some p-nitrophenylalanine dipeptides by vesicular aminopeptidase N from the porcine small intestine brush border membrane was studied. It was shown that the catalytic properties of the vesicular enzyme are very similar to those known for its solubilized counterpart. Both enzymes are inhibited by o-phenanthroline, ZnCl2 and puromycin with Ki = 10(-5)-10(-6) M. The data obtained offer new possibilities for investigating the role of aminopeptidase N in the amino acid and peptide transport across the enterocyte membrane.

Aminopeptidases↗

PubMed1984

[Proteases from the enterocytes of the porcine small intestine. Role of aminopeptidase N in the transport of dipeptides].

The kinetics of radioactive label uptake from [U-14C]Gly, L-[4.5-3H]Leu and dipeptide [U-14C]Gly-L-[4.5-3H]Leu by the brush border membrane vesicles of porcine small intestine have been studied. The effect of aminopeptidase N inhibitors and of leucine-binding protein on the accumulation rates has been investigated. A comparison of the kinetic parameters for the uptake and hydrolysis of Gly-L-Leu, has demonstrated that the dipeptide transfer includes two conjugated steps, i. e., hydrolysis catalyzed by aminopeptidase N and transport of the resultant free amino acids by a specific carrier.

Aminopeptidases↗

PubMed1982

[Thermodynamics changes in catalytic properties of immobilized enzymes].

Study of the temperature dependence of hydrolysis of the ethyl ester N-acetyl-L-tyrosine and p-nitroanilide N-succinyl-L-phenylalanine by chymotrypsin and polymaleic acid-modified chymotrypsin showed that the enthalpy and enthropy of dissociation of the enzyme-substrate complex and those of activation of the enzyme acylation in the course of catalysis increase during the native enzyme transition to its modified form. The data obtained can be explained terms of changes in the native conformation of the enzyme during its modification, which is confirmed by the previously obtained data on thermodenaturation. Some part of the energy of substrate binding is consumed for changing the conformation of the modified protein, rendering it close to the native one and thus providing a further enzymatic catalysis which is similar to that by the native enzyme.

Chymotrypsin↗

PubMed1977

[On the changes in alpha-chymotrypsin stability after its modification by polyelectrolytes].

Reversible thermal denaturation of alpha-chymotrypsin, its electrostatic complexes with carboxyl-containing polymers and the enzyme covalently bound with those polymers were studied. It was shown that the enzyme stability is affected by matrix, which manifests itself in a simultaneous decrease in enthalpy and enthropy of the reversible denaturation process and a simultaneous decrease in activation enthalpy and enthropy of denaturation. Modification and complexing of chymotrypsin with polymers has practically no effect on the activation parameters of renaturation. Differences in the original states of alpha-chymotrypsin and its derivatives and similarity of their activated states are proposed. The formation of ionic complexes of enzyme or covalent binding to polymers results in alteration of the protein native state similar to the denaturated state.

Chymotrypsin↗