ENZYMATIC-SYNTHESIS OF ALPHA-LINKED GALACTOOLIGOSACCHARIDES USING THE REVERSE REACTION OF A CELL-BOUND ALPHA-GALACTOSIDASE FROM CANDIDA-GUILLIERMONDII H-404

alpha-Linked galactooligosaccharides (alpha-GOS A from galactose, and alpha-GOS B from lactose hydrolyzates) were synthesized using the reverse reaction of a-galactosidase from Candida guilliermondii H-404. The alpha-GOS A and B were isolated and their structures were identified by methylation analysis. The main product of the disaccharides in alpha-GOS A and alpha-GOS B was the (1,6)-isomer. The remaining disaccharides consisted of (1,3)-, (1,2)-, and (1,1)-isomers. Conditions for synthesis of alpha-GOS B from lactose hydrolyzates were examined, The yield of alpha-GOS B was approximately 20% when the mixture of heat-treated cells containing alpha-galactosidase (60 U/g galactose) and 85% lactose hydrolyzates was incubated for 90 h at pH 4.5 and 50 degrees C. The alpha-GOS A and B were available as the donor substrates in transgalactosylation of alpha-galactosidase in the same manner as melibiose.