title: Purification and characterization of exo-beta-D-glucosaminidase from Aspergillus fumigatus S-26.
abstract: An extracellular 104 kDa exo-beta-d-glucosaminidase was purified and characterized from the culture supernatant of Aspergillus fumigatus S-26, which showed exceptionally strong chitosanolytic enzyme activity. The purified enzyme showed optimum pH of 3.0-6.0 and optimum temperature of 50-60 degrees C, and was stable between pH 2.0 and 10.0 and under 35 degrees C. The Km, Vmax, and kcat were determined to be 1.0 mg chitosan/ml, 7.8x10(-8) mol/s/mg protein, and 28.3 s-1, respectively. The exo-beta-D-glucosaminidase was severely inactivated by Cu2+ and Hg2+ at 10 mM. 2-Hydroxy-5-nitrobenzyl bromide, N-bromosuccinimide, and p-chloromercuribenzoic acid inhibited the enzyme. The enzyme did not degrade chitin, cellulose, and starch. The exo-beta-D-glucosaminidase did not reduce the viscosity of chitosan solutions at early stage of reaction, suggesting the exo-type of cleavage in polymeric chitosan chains. The exo-beta-D-glucosaminidase liberated only GlcN from chitosan, and GlcN plus the one-residue shortened oligomers from (GlcN)2-7. The exo-beta-D-glucosaminidase exhibited transglycosylation activity, resulting in the one-residue elongated oligomers.
authors.affiliation: Glucosamine Saccharide Materials National Research Laboratory, Department of Agricultural Chemistry, Institute of Agricultural Science and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Jung
authors.forename: Ju-Hee
authors.initials: JH
authors.lastname: Kuk
authors.forename: Kil-Yong
authors.initials: KY
authors.lastname: Kim
authors.forename: Ki-Chul
authors.initials: KC
authors.lastname: Jung
authors.forename: Ro-Dong
authors.initials: RD
authors.lastname: Park
mesh_terms: D001232:Aspergillus fumigatus / Q000187:drug effects / Q000201:enzymology*; D048271:Chitosan / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006596:Hexosaminidases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019216:Metals, Heavy / Q000494:pharmacology; D008970:Molecular Weight; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors; D014783:Viscosity
chemical_list: D004791:Enzyme Inhibitors; D019216:Metals, Heavy; D048271:Chitosan; D006596:Hexosaminidases; C064499:exo-beta-D-glucosaminidase