Pazur J H, Marchetti N T
Paul M. Althouse Laboratory, Pennsylvania State University, University Park 16802.
Carbohydr Res. 1992 Apr 6;227:215-25. doi: 10.1016/0008-6215(92)85073-9.
A valuable technique for oligosaccharide mapping, utilizing radioactive malto-oligosaccharides, multiple-ascent p.c., and radioautography, has been developed for identifying the action patterns of the glucoamylase isozymes, alpha-amylases, beta-amylase, glucosyltransferase, and glucanosyltransferase. The glucoamylase isozymes act by multi-chain mechanisms on malto-oligosaccharides and most likely on starch and glycogen. The alpha-amylases act endo-wise and randomly hydrolyze alpha-(1----4)- but not alpha-(1----6)-glucosidic bonds. These amylases may act by single-chain and/or multi-chain mechanisms, depending on the number of hydrolytic attacks per single encounter of the enzyme and the substrate. The beta-amylases hydrolyze malto-oligosaccharides by a multi-chain mechanism. A fungal glucosyltransferase from Aspergillus niger transfers glucose units by a single-chain mechanism from maltose to glucosyl acceptors to yield new gluco-oligosaccharides with alpha-(1----4) and alpha-(1----6) linkages. A novel type of transferase isolated from Bacillus subtilis acts by a multi-chain mechanism and transfers segments of 2 to 5 glucose residues from malto-oligosaccharides to acceptor co-substrates. An alpha-amylase from the same organism removes maltotriose units from the non-reducing ends of oligosaccharides by a multi-chain mechanism.
一种利用放射性麦芽寡糖、多次上行纸层析和放射自显影技术进行寡糖图谱分析的有价值方法已被开发出来，用于鉴定葡糖淀粉酶同工酶、α-淀粉酶、β-淀粉酶、葡糖基转移酶和葡聚糖基转移酶的作用模式。葡糖淀粉酶同工酶通过多链机制作用于麦芽寡糖，很可能也作用于淀粉和糖原。α-淀粉酶以内切方式作用，随机水解α-(1→4)-而非α-(1→6)-糖苷键。这些淀粉酶可能通过单链和/或多链机制起作用，这取决于酶与底物单次相遇时的水解攻击次数。β-淀粉酶通过多链机制水解麦芽寡糖。黑曲霉的一种真菌葡糖基转移酶通过单链机制将葡萄糖单位从麦芽糖转移至葡糖基受体，生成具有α-(1→4)和α-(1→6)连接的新葡糖寡糖。从枯草芽孢杆菌分离出的一种新型转移酶通过多链机制起作用，将2至5个葡萄糖残基的片段从麦芽寡糖转移至受体共底物。同一生物体中的一种α-淀粉酶通过多链机制从寡糖的非还原端去除麦芽三糖单位。
