title: Biochemical Characterization of a Novel Acidic Exochitinase from Rhizomucor miehei with Antifungal Activity.
abstract: A novel chitinase gene (RmChi44) from Rhizomucor miehei was cloned and expressed in Escherichia coli as an intracellular soluble and active protein. The recombinant chitinase (RmChi44) was purified to homogeneity and biochemically characterized. The molecular mass of RmChi44 was estimated to be 44.6 kDa on SDS-PAGE. RmChi44 displayed an acidic pH optimum of 4.5 and was stable within pH 4.5-9.0. The optimal temperature of RmChi44 was found to be 50 °C. The Km values of RmChi44 for colloidal chitin and glycol chitin were 4.02 and 1.55 mg/mL, respectively. RmChi44 hydrolyzed colloidal chitin to yield mainly N-acetyl chitobiose, exhibiting an exotype cleavage pattern. Moreover, the enzyme displayed β-N-acetylglucosaminidase activity, splitting N-acetyl COSs with degree of polymerization (DP) 2-5 into their monomer. In addition, RmChi44 showed antifungal activity against some phytopathogenic fungi. This is the first report on an exochitinase showing β-N-acetylglucosaminidase activity and antifungal activity from Rhizomucor species.
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University , Beijing 100083, China.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Yang
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University , Beijing 100083, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Fu
authors.affiliation: Bioresource Utilization Laboratory, College of Engineering, China Agricultural University , Beijing 100083, China.
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University , Beijing 100083, China.
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University , Beijing 100083, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry* / Q000494:pharmacology; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D005658:Fungi / Q000187:drug effects; D006596:Hexosaminidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D020103:Rhizomucor / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; C079639:1,4-beta-chitobiosidase; D006596:Hexosaminidases
keywords: Rhizomucor miehei; antifungal activity; characterization; chitin; exochitinase