Babiy L. The model oxidative transformations of thiamine and thiamine phosphates

Vitamin B1 and thiamin monophosphate. The modelling of oxidative transformations of TMP, TDP, thiamin and their structural analogues by action of base and oxidants. Chemical and enzymatic kinetic, spectrofotometry, NMR, chromatography. It was established that the oxidation of TMP and TDP by ferricyanide is inhibited by ferrocyanide and involves one-electron transfer step with formation cation-radical intermediate. The observed rate constants decrease if using TMP instead of TDP or thiamin. Oxidative transformations of TMP in alkaline solutions at the presence of ferricyanide or iodine are accompanied by a rapid hydrolysis of phosphate bond with formation of inorganic phosphate, thiamin and thiochrome. The effects of substituents in a position 5 of thiazolium cycle of thiamin and its structural analogues on kinetic rate constants and thermodynamic activation parameters of transformation of yellow form were shown. Bioorganic chemistry, biochemistry.