Catabolism of 3-O-methyl-D-glucopyranose by Cryptococcus laurentii

When Cryptococcus laurentii is grown on 3-O-methyl-D-glucopyranose (3-O-MeGlc), two metabolic products are methanol and an extracellular mannan. Hydrolysis of the mannan produced during growth on 3-O-MeGlc labelled with 14C in the 1 or 6 position yields mannose with retention of the labelling pattern in the carbon chain. O-Methyl-labelled substrate yields radioactive methanol. Three possible mechanisms of O-demethylation are ether cleavage, peroxidatic attack, and beta-elimination. The latter mechanism was shown to be the most likely through the use of double-labelled (3H and 14C) 3-O-MeGlc.