Role of thiamine thiol form in nitric oxide metabolism.

In alkaline media the thiamine cyclic form is converted into a thiol form (pK(a) 9.2) with an opened thiazole ring. The thiamine thiol form releases nitric oxide from S-nitrosoglutathione (GSNO).

Ultrasound-induced formation of S-nitrosoglutathione and S-nitrosocysteine in aerobic aqueous solutions of glutathione and cysteine.

S-Nitrosocompounds are formed when aqueous solutions of cysteine or glutathione are exposed to ultrasound (880 kHz) in air. The yield of the S-nitrosocompounds was as high as 10% for glutathione and 4% for cysteine of the initial thiol concentrations (from 0.1 to 10 mM) in the aqueous solutions.

Thiamine oxidative transformations catalyzed by copper ions and ascorbic acid.

In aqueous solutions containing Cu(II) ions and ascorbic acid, thiamine was observed to be oxidized to the fluorescent products thiochrome and oxodihydrothiochrome in neutral and acid media. At high initial concentrations of thiamine, thiochrome was practically the only product of thiamine oxidation. Catalase inhibited the oxidation rate approximately by 30-fold, whereas superoxide dismutase reduced the rate by only 2.

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.