|Title||Nature's many mechanisms for the degradation of oligosaccharides|
|Publication Type||Journal Article|
|Year of Publication||2004|
|Authors||Yip, VLY, Withers, SG|
|Journal||ORGANIC & BIOMOLECULAR CHEMISTRY|
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. 18.104.22.168) 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. 22.214.171.124) 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.