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Biomedical subjects

A V Finkel'shteĭn

Publications and source records attributed to A V Finkel'shteĭn.

At least 19 recordsLinked to original sources
PubMed1988

[Radionuclide assessment of microcirculatory disorders in varicose disease of the lower extremities].

Comprehensive assessment of macro- and microhemodynamics of the lower limbs in 61 patients with varicosis using radionuclide angiography and the method of 99m-Tc-pertechnetate clearance from the intracutaneous depot has shown that peripheral circulatory disturbances correspond to a stage of disease and trophic skin lesions depend on the state of microcirculation. Two types of microcirculatory disturbances have been revealed using a detailed analysis of indices of the blood circulation at the stage of decompensation: I--marked retardation of the capillary blood flow; II--the presence of arteriolovenular shunting. Radionuclide methods make it possible to unravel some problems related to the pathogenesis of disease and to obtain additional diagnostic information on radiopaque and ultrasonic investigations.

Adult↗
PubMedDate not supplied

[When and how can homologs overcome errors in the energy estimates and make the 3D structure prediction possible].

One still cannot predict the 3D fold of a protein from its amino acid sequence, mainly because of errors in the energy estimates underlying the prediction. However, a recently developed theory [1] shows that having a set of homologs (i.e., the chains with equal, in despite of numerous mutations, 3D folds) one can average the potential of each interaction over the homologs and thus predict the common 3D fold of protein family even when a correct fold prediction for an individual sequence is impossible because the energies are known only approximately. This theoretical conclusion has been verified by simulation of the energy spectra of simplified models of protein chains [2], and the further investigation of these simplified models shows that their true "native" fold can be found by folding of the chain where each interaction potential is averaged over the homologs. In conclusion, the applicability of the "homolog-averaging" approach is tested by recognition of real protein 3D structures. Both the gapless threading of sequences onto the known protein folds [3] and the more practically important gapped threading (which allows to consider not only the known 3D structures, but the more or less similar to them folds as well) shows a significant increase in selectivity of the native chain fold recognition.

Computer Simulation↗
PubMedDate not supplied

[Kinetics of folding nuclei formation in proteins].

When a protein folds or unfolds, it passes through many half-folded microstates. Only a few of them can accumulate and be seen experimentally, and this happens only when the folding (or unfolding) occurs far from the point of thermodynamic equilibrium between the native and denatured states. The universal features of folding, though, are observed in the vicinity of the equilibrium point. Here the "two-state" transition proceeds without any accumulation of metastable intermediates, and only the transition state ("folding nucleus") is outlined by its key influence on the folding/unfolding kinetics. This review covers recent experimental and theoretical studies of folding nuclei.

Animals↗
PubMedDate not supplied

[De novo proteins with a given spatial structure: new approaches to design and analysis].

Based on the molecular theory of protein structure the de novo protein was designed in order to obtain the tertiary fold which has not yet been observed in natural proteins, namely four-stranded antiparallel beta-sheet covered by two alpha-helixes. The gene coding for this protein (named albebetin) was chemically synthesized, cloned in plasmid with SP6 phage promoter and expressed in mRNA-dependent cell-free translation system. An approach was developed to study albebetin using only nanogram amounts of radio labelled protein without previous purification. The preliminary analysis of its structure by gel-filtration, urea-gradient electrophoresis and limited proteolysis revealed compactness and stability of the de novo protein.

Amino Acid Sequence↗
PubMedDate not supplied

[On prediction of folding nuclei in globular proteins].

The approach described in this paper on the prediction of folding nuclei in globular proteins with known three dimensional structures is based on a search of the lowest saddle points through the barrier separating the unfolded state from the native structure on the free-energy landscape of protein chain. This search is performed by a dynamic programming method. Comparison of theoretical results with experimental data on the folding nuclei of two dozen of proteins shows that our model provides good phi value predictions for proteins whose structures have been determined by X-ray analysis, with a less limited success for proteins whose structures have been determined by NMR techniques only. Consideration of a full ensemble of transition states results in more successful prediction than consideration of only the transition states with the minimal free energy. In conclusion we have predicted the localization of folding nuclei for three dimensional protein structures for which kinetics of folding is studied now but the localization of folding nuclei is still unknown.

Kinetics↗
PubMedDate not supplied

[Determination of the folding of globular protein chain by the self-consistent field method].

It is shown that and how it is possible to single out the chain fold which is thermo-dynamically most stable. The suggested approach is based on two physical ideas: A "molecular field" approximation permits to examine all protein structures which belong to the same "folding pattern". Only a limited set of the "potentially stable" folding patterns have to be examined. The general approach is illustrated by calculations of the stable folds for two beta-domains.

Mathematics↗
PubMedDate not supplied

[Predicting the three-dimensional structure of alpha- and beta-interferons].

Secondary structures of leukocyte alpha 1- and alpha 2-interferons and of fibroblast beta-interferon are calculated using the molecular theory of protein secondary structures. The common secondary structure calculated for alpha- and beta-interferons is used to predict the three-dimensional structures of fragments 1-110 and 111-166 of the chains (which are supposed to be quasi-independent domains). The predicted structure of the active domain I (1-110) is an "up-and-down" tetrahelical complex (in which the second helix is shorter than the others and can be missed in alpha 1-interferon) similar to the mirror-image of myohaemoerythrin. The predicted structure of domain II (111-166) is either a three-stranded beta-sheet screened from one side by two alpha-helices or a three-helical complex (similar to that in the N-domain of papain), the first structure being better consistent with the circular dichroism data of alpha-interferon and its C-end fragment.

Animals↗