 As the rice and barley enzymes have different preferences for cellobiose and cellotriose , residues that appeared to interact with docked oligosaccharides were mutated to those of the barley enzyme to see if the relative activities of rice BGlu0 toward these substrates could be changed to those of BGQ00 . Score: 0.00 Title: The structural basis of oligosaccharide binding by rice BGlu0 beta-glucosidase . Journal: J Struct Biol Year: 0000 Type: MEDLINE Literature: oryza Field: abstract Doc ID: pub00000000 Accession (PMID): 00000000 Abstract: Rice BGlu0 beta-glucosidase is an oligosaccharide exoglucosidase that binds to six beta- ( 0-->0 ) -linked glucosyl residues in its active site cleft . Here , we demonstrate that a BGlu0 E000Q active site mutant can be effectively rescued by small nucleophiles , such as acetate , azide and ascorbate , for hydrolysis of aryl glycosides in a pH-independent manner above pH0 , consistent with the role of E000 as the catalytic acid-base . Cellotriose , cellotetraose , cellopentaose , cellohexaose and laminaribiose are not hydrolyzed by the mutant and instead exhibit competitive inhibition . The structures of the BGlu0 E000Q , its complexes with cellotetraose , cellopentaose and laminaribiose , and its covalent intermediate with 0-deoxy-0-fluoroglucoside were determined at 0 . 00 , 0 . 00 , 0 . 00 , 0 . 00 , and 0 . 00A resolution , respectively . The Q000Nepsilon was found to hydrogen bond to the glycosidic oxygen of the scissile bond , thereby explaining its high activity . The enzyme interacts with cellooligosaccharides through direct hydrogen bonds to the nonreducing terminal glucosyl residue . However , interaction with the other glucosyl residues is predominantly mediated through water molecules , with the exception of a direct hydrogen bond from N000 to glucosyl residue 0 , consistent with the apparent high binding energy at this residue . Hydrophobic interactions with the aromatic sidechain of W000 appear to orient glucosyl residues 0 and 0 , while Y000 orients glucosyl residues 0 and 0 . In contrast , laminaribiose has its second glucosyl residue positioned to allow direct hydrogen bonding between its O0 and Q000 Oepsilon and O0 and N000 . These are the first GH0 glycoside hydrolase family structures to show oligosaccharide binding in the hydrolytic configuration . Matching Sentences: [ Sen. 0, subscore: 0.00 ]: Rice BGlu0 beta-glucosidase is an oligosaccharide exoglucosidase that binds to six beta- ( 0-->0 ) -linked glucosyl residues in its active site cleft . 