title: Thermostable, salt tolerant, wide pH range novel chitobiase from Vibrio parahemolyticus: isolation, characterization, molecular cloning, and expression.
abstract: A chitobiase gene from Vibrio parahemolyticus was cloned into plasmid pUC18 in Escherichia coli strain DH5 alpha. The plasmid construct, pC120, contained a 6.4 kb Vibrio DNA insert. The recombinant gene expressed chitobiase [EC 3.2.1.30] activity similar to that found in the native Vibrio. The enzyme was purified by ion exchange, hydroxylapatite and gel permeation chromatographies, and exhibited an apparent molecular weight of 80 kDa on SDS-polyacrylamide gel electrophoresis. Chitobiose and 6 more substrates, including beta-N-acetyl galactosamine glycosides, were hydrolyzed by the recombinant chitobiase, indicating its putative classification as an hexosaminidase [EC 3.2.1.52]. The enzyme was resistant to denaturation by 2 M NaCl, thermostable at 45 degrees C and active over a very unusual (for glycosyl hydrolases) pH range, from 4 to 10. The purified cloned chitobiase gave 4 closely focussed bands on an isoelectric focusing gel, at pH 4 to 6.5. The N-terminal 43 amino acid sequence shows no homology with other proteins in commercial databanks or in the literature, and from its N-terminal sequence, appears to be a novel protein, unrelated in sequence to chitobiases from other Vibrios reported and unrelated to hexosaminidases from other organisms.
authors.affiliation: Department of Biochemistry, Louisiana State University, Baton Rouge 70803.
authors.forename: B C
authors.initials: BC
authors.lastname: Zhu
authors.forename: J Y
authors.initials: JY
authors.lastname: Lo
authors.forename: Y T
authors.initials: YT
authors.lastname: Li
authors.forename: S C
authors.initials: SC
authors.lastname: Li
authors.forename: J M
authors.initials: JM
authors.lastname: Jaynes
authors.forename: O S
authors.initials: OS
authors.lastname: Gildemeister
authors.forename: R A
authors.initials: RA
authors.lastname: Laine
authors.forename: C Y
authors.initials: CY
authors.lastname: Ou
mesh_terms: D000118:Acetylglucosaminidase / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D002240:Carbohydrate Sequence; D002458:Cell Fractionation; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007700:Kinetics; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D012965:Sodium Chloride / Q000494:pharmacology*; D013379:Substrate Specificity; D014170:Transformation, Genetic; D014736:Vibrio parahaemolyticus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D012965:Sodium Chloride; D000118:Acetylglucosaminidase