Characteristics of maltose transporter activity in an ale and larger strain of the yeast Saccharomyces cerevisiae

Kinetic studies on maltose uptake by ale and larger yeasts showed lower Km and higher Vmax values than for laboratory yeasts. Eadie-Hofstee plots were biphasic and inhibition by sulphydryl reagents was consistent with low affinity uptake by a specific transporter rather than by non-specific adsorption. High affinity maltose transport by both strains was inhibited by galactose, CCCP, 2, 4,-DNP and NEM. In contrast, glucose and pCMBS inhibited high affinity transport by the ale yeast but not by the larger yeast. In the case of pCMBS the difference could result from a single amino acid change in the maltose transporter.