由碳水化合物酶催化的多分子底物反应。米曲霉α-淀粉酶对麦芽寡糖的降解

Multimolecular substrate reactions catalyzed by caabohydrases. Aspergillus oryzae alpha-amylase degradation of maltooligosaccharides.

作者信息

Allen J D, Thoma J A

出版信息

Biochemistry. 1978 Jun 13;17(12):2338-44. doi: 10.1021/bi00605a013.

Abstract

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.

摘要

米曲霉α-淀粉酶除了通过简单的糖苷键断裂外，还通过其他途径降解麦芽低聚糖。随着底物浓度的增加，替代途径的利用率也会增加，这意味着存在多分子底物机制。使用还原端标记和均匀标记的麦芽低聚糖来阐明这些替代降解机制。缩合后水解不是主要途径。得出发生了转糖基化的结论，但没有单一的转糖基化机制能够解释麦芽三糖降解的所有实验数据。相反，必须采用多种转糖基化的组合。