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Nature's many mechanisms for the degradation of oligosaccharides

TitleNature's many mechanisms for the degradation of oligosaccharides
Publication TypeJournal Article
Year of Publication2004
AuthorsYip, VLY, Withers, SG

Recent work on the mechanistic elucidation of the polysaccharide lyases, the alpha-1,4-glucan lyases, and the Family 4 glycosidases have demonstrated that nature has evolved to use elimination steps for the degradation of oligosaccharides. The polysaccharide lyases ( E. C. 4.2.2.-) have been shown to cleave uronic acid-containing polysaccharides via a stepwise E1cB mechanism. The mechanism of the alpha-1,4-glucan lyases ( E. C. is similar to the Family 31 glycosidases, forming a covalent glycosyl-enzyme intermediate, which is subsequently cleaved by an E1-like E2 mechanism. Meanwhile, the Family 4 glycosidases ( E. C. are suggested to undergo an oxidation-elimination-addition-reduction sequence. These three groups of enzymes are examples of stark contrast to the vast number of well-characterized glycosidases ( E. C. 3.2.1.-), which utilize either the direct or double displacement mechanisms as proposed by Koshland over 50 years ago.