title: Enhancement of the thermostability of a recombinant beta-agarase, AgaB, from Zobellia galactanivorans by random mutagenesis.
abstract: Random mutagenesis was performed on beta-agarase, AgaB, from Zobellia galactanivorans to improve its catalytic activity and thermostability. The activities of three mutants E99K, T307I and E99K-T307I were approx. 140, 190 and 200%, respectively, of wild type beta-agarase (661 U/mg) at 40 degrees C. All three mutant enzymes were stable up to 50 degrees C and E99K-T307I had the highest thermostability. The melting temperature (Tm) of E99K-T307I, determined by CD spectra, was increased by 5.2 degrees C over that of the wild-type enzyme (54.6 degrees C). Activities of both the wild-type and E99K-T307I enzymes, as well as their overall thermostabilities, increased in 1 mM CaCl2. The E99K-T307I enzyme was stable at 55 degrees C with 1 mM CaCl2, reaching 260% of the activity the wild-type enzyme held at 40 degrees C without CaCl2.
authors.affiliation: Department of Pharmaceutical Engineering, College of Medical Life Sciences, Silla University, Busan, 617-736, Korea.
authors.forename: Min-Kyung
authors.initials: MK
authors.lastname: Jang
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Lee
authors.forename: Dong-Geun
authors.initials: DG
authors.lastname: Lee
authors.forename: Nam-Young
authors.initials: NY
authors.lastname: Kim
authors.forename: Ki Hwan
authors.initials: KH
authors.lastname: Yu
authors.forename: Hye Ji
authors.initials: HJ
authors.lastname: Jang
authors.forename: Suhkman
authors.initials: S
authors.lastname: Kim
authors.forename: Andre
authors.initials: A
authors.lastname: Kim
authors.forename: Sang-Hyeon
authors.initials: SH
authors.lastname: Lee
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D002122:Calcium Chloride / Q000378:metabolism; D002942:Circular Dichroism; D004252:DNA Mutational Analysis; D004795:Enzyme Stability; D041965:Flavobacteriaceae / Q000201:enzymology* / Q000235:genetics; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics; D006358:Hot Temperature; D016296:Mutagenesis; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics; D020125:Mutation, Missense; D055550:Protein Stability; D044366:Transition Temperature
chemical_list: D001426:Bacterial Proteins; D050505:Mutant Proteins; D006026:Glycoside Hydrolases; C019624:agarase; D002122:Calcium Chloride