Catalytic properties of a mutant β-galactosidase from Xanthomonas manihotis engineered to synthesize galactosyl-thio-β-1,3 and -β-1,4-glycosides

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• 作者：Young-Wan Kim ; Hongming Chen ; Jin Hyo Kim and Stephen G. Withers
• 关键词：Glycoside hydrolase Family 35 ; Xanthomonas manihotis β ; -galactosidase ; Acid/base catalyst ; Thioglycoligase ; Thioglycosides
• 刊名：FEBS Letters
• 出版年：2006
• 出版时间：7 August 2006
• 年：2006
• 卷：580
• 期：18
• 页码：4377-4381
• 全文大小：155 K

文摘

The identity of the acid/base catalyst of the Family 35 β-galactosidases from Xanthomonas manihotis (BgaX) has been confirmed as Glu184 by kinetic analysis of mutants modified at that position. The Glu184Ala mutant of BgaX is shown to function as an efficient thioglycoligase, which synthesises thiogalactosides with linkages to the 3 and 4 positions of glucosides and galactosides in high (>80 % ) yields. Kinetic analysis of the thioglycoligase reveals glycosyl donor K_m values of 1.5–21 μM and glycosyl acceptor K_m values from 180 to 500 μM. This mutant should be a valuable catalyst for the synthesis of metabolically stable analogues of this important glycosidic linkage.