부산대학교 도서관

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jsb.2008.03.008 Byline: Chomphunuch Songsiriritthigul (a)(b), Supansa Pantoom (a), Adeleke H. Aguda (c)(d), Robert C. Robinson (c), Wipa Suginta (a) Keywords: Chitinase; Chitin oligosaccharide; Crystal structure; The slide-and-bend mechanism; Vibrio harveyi Abstract: This research describes four X-ray structures of Vibrio harveyi chitinase A and its catalytically inactive mutant (E315M) in the presence and absence of substrates. The overall structure of chitinase A is that of a typical family-18 glycosyl hydrolase comprising three distinct domains: (i) the amino-terminal chitin-binding domain; (ii) the main catalytic ([alpha]/[beta]).sub.8 TIM-barrel domain; and (iii) the small ([alpha]+[beta]) insertion domain. The catalytic cleft of chitinase A has a long, deep groove, which contains six chitooligosaccharide ring-binding subsites (-4)(-3)(-2)(-1)(+1)(+2). The binding cleft of the ligand-free E315M is partially blocked by the C-terminal (His).sub.6-tag. Structures of E315M-chitooligosaccharide complexes display a linear conformation of pentaNAG, but a bent conformation of hexaNAG. Analysis of the final 2F.sub.o - F.sub.c omit map of E315M-NAG6 reveals the existence of the linear conformation of the hexaNAG at a lower occupancy with respect to the bent conformation. These crystallographic data provide evidence that the interacting sugars undergo conformational changes prior to hydrolysis by the wild-type enzyme. Author Affiliation: (a) School of Biochemistry, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand (b) National Synchrotron Research Center, Nakhon Ratchasima 30000, Thailand (c) Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Singapore (d) Department of Biology, University of Virginia, Charlottesville, VA 22904, USA Article History: Received 13 December 2007; Revised 14 March 2008; Accepted 18 March 2008