Effect of oxythiamin on growth rate, survival ability and pyruvate decarboxylase activity in Saccharomyces cerevisiae

Oxythiamin is one of the antivitamin derivatives of thiamin which, after phosphorylation, can be bound to the catalytic centre of thiamin-dependent enzymes and inhibit these enzymes. In this work the influence of oxythiamin on the growth rate, survival and the activity of pyruvate decarboxylase of Saccharomyces cerevisiae (s288c) was investigated. Oxythiamin decreased both the growth rate and survival ability of yeast cells. Moreover, in three-day-old cultures on a medium with oxythiamin, an increase of pyruvate decarboxylase activity was observed. This unusual effect may be in response to the earlier inhibition of pyruvate decarboxylase. A high concentration of pyruvate in the cell extracts taken from the medium with oxythiamin was found. This accumulation of pyruvate could provide for enhanced biosynthesis of the pyruvate decarboxylase apoform and an increase of enzyme activity.