Biomedical subjects

D T Zakrzhevskaya

Publications and source records attributed to D T Zakrzhevskaya.

3 recordsLinked to original sources

PubMed1995

Principles of symmetrical organization for the pyruvate dehydrogenase complex.

The experimentally observed phenomenon of non-equimolarity for enzyme components, assembled into multienzyme complexes of the 2-oxo acid dehydrogenases family, is structurally interpreted to predict the only possible stable symmetrical distribution of peripheral components on the complex core. To obey the equivalent neighboring, that is necessary for unique self-assembled structures, we should deduce discrete conformational states for core subunits, those with different affinity for peripheral components. Two kinetically different types of substrate-intermediate pathways through the lipoyl network of the mammalian pyruvate dehydrogenase complex follow from this structural theory. The theory predicts unusual kinetic behavior for the multienzyme complex.

Animals↗

PubMed1994

Activity oscillations predicted for pyruvate dehydrogenase complexes.

A kinetic model for the pyruvate dehydrogenase complex is analyzed. The model takes into account intermediate channeling through the lipoyl network attached to the complex core, as well as inter-related regulatory effects of protein X acetylation and enzyme phosphorylation. The model predicts undamped oscillations of enzyme activity.

Kinetics↗

PubMed1986

Proteins tightly bound to DNA and DNA-synthesizing activity of nucleoids from Escherichia coli.

Membrane-attached nucleoids were isolated from E. coli and separated from proteins by 2 M NaCl. Disintegration of such nucleoids by ultrasound and subsequent centrifugation resulted in the formation of two fractions: a sediment (fraction I) and a supernatant (fraction II). The protein:DNA ratio of fraction I was equal to 27 and was different from that to fraction II (2.6). More than 70% of the proteins not dissociating at 2 M NaCl and bound to DNA of both fractions were polypeptides with molecular weights (Mw) of 31,000-23,000 daltons (31-23 Kdal). After pulse labelling of the cells with [3H]-thymidine, the specific radioactivity of newly synthesized DNA associated with fraction I was shown to be considerably higher than that of fraction II. The analysis of DNA-synthesizing activities in fractions I and II showed that both nucleoid fractions contained DNA polymerase I. After dissolving the two fractions in 8 M urea - 0.15% sodium dodecylsulphate (SDS) they were chromatographed on hydroxyapatite. DNA-protein complexes were obtained that did not dissociate at 4 M guanidine X HCl - 5 M urea and 1% SDS. The main protein of the complexes was a 31 Kdal polypeptide tightly bound to DNA.

Bacterial Proteins↗