title: Purification and characterization of two chitosanase isoforms from the sheaths of bamboo shoots.
abstract: Two thermally stable chitosanase isoforms were purified from the sheaths of chitosan-treated bamboo shoots. Isoforms A and B had molecular masses of 24.5 and 16.4 kDa and isoelectric points of 4.30 and 9.22, respectively. Using chitosan as the substrate, both isoforms functioned optimally between pH 3 and 4, and the optimum temperatures for the activities of isoforms A and B were 70 and 60 °C, respectively. The kinetic parameters K(m) and V(max) for isoform A were 0.539 mg/mL and 0.262 μmol/min/mg, respectively, and for isoform B were 0.183 mg/mL and 0.092 μmol/min/mg, respectively. Chitosans were susceptible to degradation by both enzymes and could be converted to low molecular weight chitosans between 28.2 and 11.7 kDa. Furthermore, the most susceptible chitosan substrates were 50-70 and 40-80% deacetylated for isoforms A and B, respectively. Both enzymes could also degrade chitin substrates with lower efficacy. N-Bromosuccinimide and Woodward's reagent K strongly inhibited both enzymes.
authors.affiliation: Department of Food and Nutrition, Providence University, Shalu, Taichung, Taiwan, Republic of China.
authors.forename: Shou-Kuo
authors.initials: SK
authors.lastname: Hsu
authors.forename: Yun-Chin
authors.initials: YC
authors.lastname: Chung
authors.forename: Chen-Tien
authors.initials: CT
authors.lastname: Chang
authors.forename: Hsien-Yi
authors.initials: HY
authors.lastname: Sung
mesh_terms: D031723:Bambusa / Q000201:enzymology*; D001974:Bromosuccinimide / Q000494:pharmacology; D002686:Chitin / Q000378:metabolism; D048271:Chitosan / Q000737:chemistry / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007527:Isoenzymes; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D008970:Molecular Weight; D018520:Plant Shoots / Q000201:enzymology; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008670:Metals; D002686:Chitin; D048271:Chitosan; D004492:Edetic Acid; D006026:Glycoside Hydrolases; C019868:chitosanase; D001974:Bromosuccinimide