Multimolecular substrate reactions catalyzed by carbohydrases. Aspergillus oryzae α-amylase degradation of maltooligosaccharides

Aspergillus oryzae alpha-amylase degrades maltooligosaccharides by other pathways besides simple glycosidic bond scission. The utilization of the alternate pathways increases with the concentration of substrate implicating a multimolecular substrate mechanism. Reducing-end labeled and uniformly labeled maltooligosaccharides were used to elucidate these alternate degradation mechanisms. Condensation followed by hydrolysis is not a significant pathway. Transglycosylation is concluded to occur, but no single transglycosylation mechanism can account for all of the experimental data for maltotriose degradation. Rather, a combination of transglycosylations must be invoked.