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Biomedical subjects

M A Rozenfel'd

Publications and source records attributed to M A Rozenfel'd.

At least 19 recordsLinked to original sources
PubMed1991

Mechanism of aggregation of fibrinogen molecules: the influence of fibrin-stabilising factor.

The physicochemical mechanism of aggregation of fibrinogen has been investigated in the presence and absence of fibrin-stabilising factor (factor XIIIa). Data from elastic and inelastic light-scattering and viscometry show that molecules of fibrinogen undergo a spontaneous modification of their carboxyl terminals and bind 'end to end' into flexible polymer chains. On attaining a critical length, the single-filament polymers twist into a coil and aggregate to form branched molecules in which the segments are packed sufficiently densely to resemble strongly hydrated globular particles. The formation, under the influence of factor XIIIa, of epsilon/gamma-glutamyl-lysine covalent bonds produces only insignificant changes in the spatial organisation of the fibrinogen aggregates. Covalent dimerisation of the gamma-chains restricts the structural flexibility of the polymers, but linking of the alpha-chains provides progressive compaction of the structure with increase in molecular weight. Electrophoresis of reconstituted samples shows that the coil-shaped chains of fibrinogen oligomers prevent the complete enzymatic linking of the gamma-chains. The results of this work suggest that the accelerated assembly of multimolecular aggregates, seen in the presence of factor XIIIa, may be explained by the stabilisation of intermediate complexes of fibrinogen, which makes the spontaneous transition from a stable native state to the activated state irreversible.

Animals↗
PubMed1988

[Interaction of ovomucoid from duck egg white with serine proteinases].

The interaction of highly purified duck egg white ovomucoid with trypsin and chymotrypsin was studied. It was found that the ovomucoid molecule contains two equally effective trypsin-binding sites which, in their turn, comprise lysine residues and one independent chymotrypsin-binding site. The values of inhibition constants were determined and the changes in free energy, enthalpy and entropy during the ovomucoid interaction with trypsin and chymotrypsin were established. It was shown that the inhibitor affinity for the enzymes does not change at low degrees of free amino groups modification.

Amino Acids↗
PubMed1987

[Effect of low-molecular peptides on the transformation of fibrinogen into fibrin].

The influence of synthetic peptides on fibrinogen transformation to fibrin under the action of thrombin and fibrin-monomer polymerization was investigated. Peptides Gly-Pro-Arg-Pro; Gly-Pro-Arg-Pro-Lys; Gly-Pro-Arg-Pro-Lys-Boc; Gly-Pro-Arg-Pro-Arg are specific inhibitors of fibrin formation. These peptides interfere with the hydrolysing effect of thrombin due to binding to the central domain of fibrinogen. The interaction of peptides with peripheral D-domains of fibrin-monomer may account for polymerization inhibition. The latter peptide has the largest anticoagulation activity. It is likely that arginine in the fifth position stabilizes the structure of the peptides, with the additional epsilon NH2-group activating its interaction with protein.

Fibrin↗
PubMed1984

[Antifibrinolytic effect of heparin].

The effect of heparin on non-stabilized fibrin hydrolysis by plasmin was investigated. Using analytical centrifugation in the presence of heparin, the existence of a high molecular weight fraction (sedimentation coefficient 17S) was demonstrated. Electrophoretic analysis revealed the presence of less degradable early, intermediate and late fibrin hydrolysis products. It is concluded that the molecular mechanisms of these effects are due to the direct action of heparin on the fibrin-monomer molecule which provides for the inhibition of peptide side chains localized between residues 15 Gly-53 Lys in the NH2-terminal part of the B beta-chain. The universal mechanisms underlying the anti-fibrinolytic activity of high molecular weight inhibitors of fibrin polymerization and aggregation are discussed.

Antithrombin III↗
PubMed1983

[Fibrinogen fragment D - inhibitor of fibrinolytic processes].

The effect of fragment D, the end product of fibrinogen degradation, on the course of fibrinolytic reactions and fibrinogenolysis induced by plasmin was studied. It was shown that fragment D beside a high antipolymerizing activity also exerts antifibrinolytic and antifibrinogenolytic action. It was demonstrated electrophoretically that exogenous fragment D can inhibit plasmin degradation of fibrin and fibrinogen at all stages of proteolysis without having direct influence on plasmin. It is assumed that the nature of the antipolymerizing and antifibrinolytic activities of fragment D is determined by dissociating fibrin monomer-fragment D complexes.

Fibrin Fibrinogen Degradation Products↗
PubMed1983

[Interaction of synthetic peptides with the individual components of the blood coagulation system].

Spectrophotometry and viscosimetry were used to examine the interaction of taftcin and its decomposition products with individual components of the blood coagulation system. Peptides with free amino groups at the N-end were found to form complexes with heparin. The presence of free carboxylic groups at the C-end provided for their interaction with fibrinogen. In both the cases, the leading roles are played by electrostatic forces that determine the weakness of the effects seen. Taftcin has a negligible antipolymerization activity at the expense of the Pro-Arg sequence presence at the C-end.

Animals↗