Thiamine Derivatives of Disulfide Type. III. Enzyme Systems in Rat Intestine contributed for Thiamine Formation from the Disulfide Type Derivatives

Abstract

Assuming glutathione (GSH) as the main part of thiol group contributing for thiamine formation in gut wall from disulfide type derivatives, i.e., thiamine propyl disulfide (TPD) and thiamine disulfide (TDS), the reactivity between GSH and TPD or TDS and the characteristics of enzyme system in gut wall was studied. The following conclusions were drawn from the result presented. 1) The rate constant determined at 37° and pH 7.4 was 9.83×10² for TPD and GSH, 3.7×10 for GSH and glutathione propyl disulfide, 1.78×10³ for GSH and TDS, and 3.72×10³ for GSH and thiamine glutathione disulfide in liter/mole min, respectively. 2) The enzyme preparation was obtained by dialysis of rat gut wall homogenate. The activity was examined under the presence of GSH and NADPH and K_m=6.25×10^-5 M/liter and optimal pH=7.4 were same as that of glutathione reductase from rat liver. 3) The mechanism proposed for thiamine formation in gut lumen confirmed as the coupled system shown by Eq. (1), (2), and (3).