Abstract
Washed cells of Staphylococcus aureus FDA 209P, when incubated with thiamine (B_1) in the medium having low ionic strength, adsorbed the vitamin nonenzymatically. The amount of B_1 adsorbed could not be ignored when uptake reaction was considered. Lower temperature and lower ionic strength favoured the adsorption. The ^<14>C-thiamine adsorbed by the cell, when added to the new medium containing unlabeled B_1,was exchanged immediately with the outer B_1. In its adsorption equilibrium, which was attained in approximately 40 seconds, the concentration difference between adsorbed and not adsorbed B_1 was several hundred. Dissociation constant of the adsorption reaction was 2.0×10^<-5>M. Boiled cells adsorbed B_1 to about the same amount as unboiled cells or even more than them. Between pH 4 and 9,the cells adsorbed more B_1 when more acidic medium was used. Adsorption of free B_1 was suggested as ionic one. TMP (approximately 1/10 of B_1) and TDP (approximately 1/20 of B_1) were also adsorbed, but some different mechanism was presumed to exist in the adsorption of TDP.
