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.

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We studied the dose-dependent induction of in vivo adaptive response in the bone marrow and blood of mice exposed to low-intensity radiation of He-Ne laser (633 nm) and X-ray radiation by the severity of cytogenetic injury and intensity of ROS production, respectively. Induction of the adaptive response in mice preexposed to He-Ne laser and X-ray radiation depended on the adaptive dose and the interval between the adaptive and main doses and correlated with changes in ROS generation. The adaptive response after exposure to low-intensity ionizing and non-ionizing radiation was observed in the same dose range, which attests to similar mechanisms of its induction.

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.

We studied the effect of exposure to helium-neon laser (dose range 0.16-50 mJ/cm) on activation of natural protection reserve in mice using the adaptive response test. DNA comets method revealed a protective response manifested in DNA damage level in whole blood leukocytes of mice and in lymphoid organs by the thymus and spleen weight index; preexposure to laser did not induce the adaptive response. ROS level in the whole blood was assessed by the level of zymosan-induced luminol chemiluminescence. In mice subjected to adaptive laser irradiation in doses of 0.16-5 mJ/cm followed by X-ray irradiation in a dose of 1.5 Gy, the activation index calculated as the ratio of induced to spontaneous area of luminescence was by 1.4 times lower than that in non-irradiated animals, which attested to reduced ROSgeneration reserve capacity of neutrophils.