Abstract
Modified thiamine compounds were easily converted to thiamine in the culture of E.coli. Disulfide-compounds, such as thiamine propyldisulfide (TPD) and O-benzoylthiamine disulfide were more easily converted to thiamine than S-acyl-compounds, such as O, S-dibenzoylthiamine and O, S-dicarbethoxythiamine. TPD was reduced to thiamine by the cell-free extract (CFE) of E.coli but not by the cell debris. TPD was more strongly reduced to thiamine by the CFE in its alkaline range than in its neutral range and at higher temperature (60〜100℃) than 37℃. The CFE, when heated for 5 min., was shown to reduce TPD more strongly but when heated for over 30 min., it was partly inactivated to reduce TPD. Such SH-blocking reagents as PCMB, NEM and MIA, when added to the CFE, or dialysis of the CFE weakened the reduction of TPD by the CFE. Thus SH-groups of protein in the CFE were shown to be responsible to the reduction of TPD by the CFE.
