Glycoside hydrolases types

In spite of the apparent extreme diversity of the / -(l- 4) glycans— from crystalline cellulose to components of bacterial cell walls—the similarity of the environments around their / -(1— 4) glycosidic linkage raises the question of a common catalytic site structure in the various / -(l- 4) glycoside hydrolases. This chapter will review the evidence for and against a general lysozyme type mechanism. 

The Type C CBMs were first discovered as lectins with small-sugar-binding activity and have only subsequently been included as CBMs due to their discovery in a number of glycoside hydrolases. This family of CBMs is found exclusively in xylanases. Differences between Type B and Type C CBMs can be small, but the hydrogen-bonding network between protein and ligand is more extensive in Type C CBMs than in Type B modules. 

Enzyme-catalyzed glycoside cleavages (and syntheses) are considered by Hehre [6,8] to be variants of the same reaction (O Eq. 1), catalyzed by a single type of enzyme, the glycosylases, comprising glycoside hydrolases, glycosyl transferases, phosphorylases and certain lyases. 

In contrast to the previously described pullulanases, pullulan hydrolases types I and II are unable to hydrolyze a-l,6-glycosidic linkages in pullulan or in branched... 

A further subdivision of glycoside hydrolases into taka and emulsin types is based corresponding unsubstitutea phenylglycosides (93, 100, 105). ... 

Fujita, K., Oura, R, Nagamine, N., Katayama, T., Hiratake, J., Sakata, K., Kumagai, H., and Yamamoto, K. 2005. Identification and molecular cloning of a novel glycoside hydrolase family of core 1 type O-glycan-specific endo-alpha-iV-acetylgalactosaminidase from Bifidobacterium longum. J. Biol. Chem. 280 37415-37422. 

Glycoside hydrolases have two types, one is an endo- y Q and the other is an exo-type enzyme 24). For the enzymatic polymerization, endo-Xypt enzymes are normally utilized, whose shape at the catalytic domain looks like cleft (25). At... 

Enzymes classified into oxazoline intermediate type are typically chitinase and hyaluronidase. Chitinase from Bacillus sp. (EC 3.2.1.14) belonging to the glycoside hydrolase family 18 primarily catalyzes hydrolysis of (1— 4)-jff-A-acetylglucosaminide linkage in chitin (30,32,33). The hydrolysis mechanism is postulated to proceed through the substrate-assisted mechanism as follows (Figure 3). 

CGTase is a kind of glycoside hydrolases, and according to the deference in the conformation of the anomeric carbon atom of glycosidic bonds subjected to hydrolysis, there are two kinds of enzyme catalytic mechanisms One is conformation inversion type (Fig. 2.2(a)), and the other is conformation keeping... 

---