TAILIEUCHUNG - Báo cáo khoa học: Degradation of chitosans with chitinase B from Serratia marcescens Production of chito-oligosaccharides and insight into enzyme processivity

Family 18 chitinases such as chitinase B (ChiB) fromSerratia marcescens catalyze glycoside hydrolysis via a mechanism involving the N-acetyl group of the sugar bound to the)1 subsite. We have studied the degradation of the soluble heteropolymer chitosan, to obtain further insight into catalysis in ChiB and to experimentally assess the proposed processive action of this enzyme. Degradation of chitosans with varying degrees of acetylation was monitored by following the size-distribution of oligomers, and oligomers were isolated and partly sequenced using 1 H-NMR spectroscopy | iFEBS Journal Degradation of chitosans with chitinase B from Serratia marcescens Production of chito-oligosaccharides and insight into enzyme processivity Audun Sdrbotten1 Svein J. Horn2 Vincent G. H. Eijsink2 and Kjell M. Varum1 1 Norwegian Biopolymer Laboratory NOBIPOL Department of Biotechnology Norwegian University of Science and Technology Trondheim Norway 2 Department of Chemistry Biotechnology and Food Science AgriculturalUniversity of Norway As Norway Keywords chitinase B chitosan degradation oligosaccharides processive enzymes subsite analysis Correspondence K. M. Varum Norwegian Biopolymer Laboratory NOBIPOL Department of Biotechnology Norwegian University of Science and Technology 7491 Trondheim Norway Fax 47 73591283 Tel 47 73593324 E-mail Received 12 October 2004 accepted 18 November 2004 doi Family 18 chitinases such as chitinase B ChiB from Serratia marcescens catalyze glycoside hydrolysis via a mechanism involving the N-acetyl group of the sugar bound to the -1 subsite. We have studied the degradation of the soluble heteropolymer chitosan to obtain further insight into catalysis in ChiB and to experimentally assess the proposed processive action of this enzyme. Degradation of chitosans with varying degrees of acetylation was monitored by following the size-distribution of oligomers and oligomers were isolated and partly sequenced using 1H-NMR spectroscopy. Degradation of a chitosan with 65 acetylated units showed that ChiB is an exoenzyme which degrades the polymer chains from their nonreducing ends. The degradation showed biphasic kinetics the faster phase is dominated by cleavage on the reducing side of two acetylated units occupying subsites -2 and -1 while the slower kinetic phase reflects cleavage on the reducing side of a deacetylated and an acetylated unit bound to subsites -2 and -1 respectively . The enzyme did not show preferences with respect to acetylation of the sugar

• Báo cáo khoa học
• Report medicine
• traditional medicine
• scientific reports
• medical knowledge
• medical research
• analysis of cytoplasmic
• oxidation
• Crystal structure
• bacteria
• hemoglobin
• medicine
• cell proliferation
• breast cancer
• chemical reaction
• gastric cancer
• hormone medicine
• tumor cells
• biochemical studies
• environmental medicine