ENZYMATIC-SYNTHESIS OF MONOSACCHARIDE AMINO-ACID CONJUGATES

Enzymatic condensation between amino acids and monosaccharides was studied. A screening involving the OH-containing amino acids serine and threonine and the monosaccharide substrates for the enzymes alpha-N-acetylgalactosaminidase, alpha-galactosidase, alpha-mannosidase, beta-xylosidase, and beta-galactosidase was carried out. Enzymatic condensation was observed with alpha-mannosidase and alpha-N-acetylgalactosaminidase. Products were only detected under reversed hydrolysis conditions, not under transglycosylation conditions with activated substrates. Both L- and D-isomers of the amino acids were substrates for alpha-mannosidase and alpha-N-acetylgalactosaminidase. A closer investigation of the formation of alpha-D-Man-(1-3')-L-Ser and alpha-D-GalNAc-(1-3')-L-Ser was carried out at 35-degrees-C and 55-degrees-C, at which temperature the reaction rates were greatly increased.