Reduction of nitrite by glycosylated amino acids and glycosylated albumin.

Glycosylated amino acids and glycosylated human serum albumin reduce nitrite to nitric oxide under anaerobic conditions. The amount of nitric oxide produced was recorded by generation of nitrosoHb from deoxyHb. Without preincubation after the addition of sodium nitrite, glucose or a mixture of glucose with amino acid or serum albumin did not cause spectrophotometrically detectible transformation of deoxyHb into nitrosoHb.

Reduction of methemoglobin and ferricytochrome c by glycosylated amino acids and albumin.

The fraction of Amadori products gradually decreased during heavy glycosylation of amino acids and human serum albumin while the amount of a colored product with the maximum fluorescence at 420 nm decreased. The addition of the produced ketoamines of amino acids to the solution of native albumin quenched its own fluorescence due to generation of a Schiff base with amino groups of the protein. Carbonyl-containing Amadori products obtained during the early steps of glycosylation were less potent electron donors than amino acids more heavily modified by the carbohydrate.

Generation of NO during oxidation of hemoglobin ferroforms by nitrite.

The oxidation of hemoglobin solutions or erythrocyte suspensions containing a mixture of deoxyHb and oxyHb by NaNO2 (under decreased partial pressure of dissolved O2) resulted in the generation of metHb and nitrosoHb. The maximum amount of nitrosoHb was generated during the oxidation of deoxyHb. An increase in oxygen content was accompanied with increased generation of metHb, which was the only hemoglobin form under aerobic conditions.

Glutathione oxidation under the action of sodium nitrite on hemoglobin.

The reaction of oxidation of oxyhemoglobin (oxyHb) to methemoglobin (metHb) by sodium nitrite in the presence of reduced glutathione is characterized by the changed ratios between the slow and rapid reaction phases. The duration of the lag phase increases as the glutathione concentration in the solution rises. The autocatalytic phase was inhibited and glutathione was oxidized to the disulfide form.

Long-term preservation of microbial ecosystems in permafrost.

It has been established that significant numbers (up to 10 million cells per gram of sample) of living microorganisms of various ecological and morphological groups have been preserved under permafrost conditions, at temperatures ranging from -9 to -13 degrees C and depths of up to 100 m, for thousands and sometimes millions of years. Preserved since the formation of permafrost in sand-clay sediments of the Pliocene-Quaternary period and in paleosols and peats buried among them, these cells art the only living organisms that have survived for a geologically significant period of time. The complexity of the microbial community preserved varies with the age of the permafrost.