Crystal Structure of Cel44A, a Glycoside Hydrolase Family 44 Endoglucanase fromClostridium thermocellum

Yu Kitago, Shuichi Karita, Nobuhisa Watanabe, Masakatsu Kamiya, Tomoyasu Aizawa, Kazuo Sakka, Isao Tanaka
2007 Journal of Biological Chemistry  
The crystal structure of Cel44A, which is one of the enzymatic components of the cellulosome of Clostridium thermocellum, was solved at a resolution of 0.96 Å . This enzyme belongs to glycoside hydrolase family (GH family) 44. The structure reveals that Cel44A consists of a TIM-like barrel domain and a ␤-sandwich domain. The wild-type and the E186Q mutant structures complexed with substrates suggest that two glutamic acid residues, Glu 186 and Glu 359 , are the active residues of the enzyme.
more » ... s of the enzyme. Biochemical experiments were performed to confirm this idea. The structural features indicate that GH family 44 belongs to clan GH-A and that the reaction catalyzed by Cel44A is retaining type hydrolysis. The stereochemical course of hydrolysis was confirmed by a 1 H NMR experiment using the reduced cellooligosaccharide as a substrate.
doi:10.1074/jbc.m706835200 pmid:17905739 fatcat:aybdlamu3nfqbi7eyh33qir6dm