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L I Elfimova

Publications and source records attributed to L I Elfimova.

6 recordsLinked to original sources
PubMed1977

[Effect of coenzyme on conformational stability of glyceraldehyde-3-phosphate dehydrogenase from muscles of ecto- and endothermic animals].

The stabilizing effect of the coenzyme (NAD) on the structure of glyceraldehyde-3-phosphate dehydrogenase from lamprey and porcine muscles with respect to proteolysis and heat denaturation was studied. The process of heat denaturation was followed by the changes in specific activity of the enzymes; that of proteolysis--by the changes in specific activity and circular dichroism. It was shown that in both cases NAD at saturating concentration exerts a far weaker stabilizing effect on the structure of glyceraldehyde-3-phosphate dehydrogenase from lamprey muscle than on that of the porcine muscle enzyme. The coensyme-dependent stabilization of lamprey muscle glyceraldehyde-3-phosphate dehydrogenase does not differ from that of mammalian muscle enzyme. Possible interrelationship between the phenomenon observed and the molecular mechanism of thermal adaptation in the cold-blooded animals is discussed.

Adaptation, Physiological↗
PubMed1977

[T2 DNA, modified by 2,2,6,6-tetramethyl-4-bromoacetooxypiperidine-i-oxyl as a template for RNA polymerase from E. coli B].

T2-DNA was modified by 2,2,6,6-tetramethyl-4-bromoacetooxypiperidine-1-oxyl (I) at different NaCl concentrations (10(-1) M NaCl--10(-4) M NaCl). Modified DNA were investigated as templates for the RNA-polymerase from E. coli B. It was shown that T2-DNA modified I in 0,1 M NaCl completely preserves the native secondary structure, has a low degree modification (1 molecule I per 1000-2000 nucleotide pairs), but is a noneffective template for the RNA-polymerase from E. coli B (20%-40% as compared with unmodified T2-DNA). Under these conditions the modification occurs probably at the "weakest" (readily melting) sites of DNA. The role of these "weak" sites on DNA as promotors is discussed. The modification of T2-DNA by reagnet I has a stronger inhibitory effect on the total RNA synthesis than on the RNA-synthesis stable to rifampicin. Possible existence of two kinds of "early" promotors on T2-DNA is assumed.

Coliphages↗
PubMedDate not supplied

[Lactate dehydrogenase in an interpolyelectrolyte complex. Function and stability].

A new method for encapsulating enzymes by multilayer polyelectrolyte coating is proposed. The method consists in a stepwise adsorption of polyelectrolytes from solution onto protein aggregates formed by salting out the proteins in highly concentrated salt solutions. Polystyrene sulfonate and fluorescence-labeled polyalylamine were used for capsule formation. The size of lactate dehydrogenase aggregates covered by four layer pairs of electrolytes was 1-5 microns, as indicated by fluorescence microscopy. The catalytic characteristics and stability of pig muscle lactate dehydrogenase (EC 1.1.1.13) incapsulated in multilayer electrolyte complex obtained by this method were studied. It was found that the affinity of the substrate pyruvate for the enzyme in the polyelectrolyte complex (K(M)) did not essentially change as compared with the free enzyme. Incapsulated lactate dehydrogenase showed the following features that distinguish it from the free form: (1) the lifetime in diluted solutions increases from 30 min (without capsules) to 1-2 days (in capsules); (2) a higher stability to basic denaturation (up to pH 10); and (3) the absence of substrate inhibition of enzyme in the polyelectrolyte complex. The changes in the catalytic characteristics of incapsulated lactate dehydrogenase are discussed in terms of an increase in effective pK values of amino acid perturbed by polyelectrolyte coating of enzyme.

Animals↗
PubMedDate not supplied

[Non-linear, non-competitive inhibition of lactate dehydrogenase with carboxylic acid anions (substrate analogues)].

The carboxylic acid anions are shown to inhibit lactate dehydrogenase in a non-competitive manner at pH 8.5. The inhibitory effect of different carboxylates used increases in the direction acetate leads to formate leads to methacrylate. Non-competitive inhibition by carboxylates has a non-linear character with effective Hill exponent depending on the inhibitor concentration increasing to the value n approximately equal to 2 when inhibitor concentration increases. The kinetic model is proposed to account for non-linear non-competitive inhibition in consequence of the abortive ternary complexes formation in two enzyme conformations. The substrate analogues properties that result in non-competitive inhibition of lactatedehydrogenase are considered.

Animals↗