title: Characterization of an exo-beta-D-fructosidase from Streptococcus mutans Ingbritt.
abstract: An extracellular enzyme beta-D-fructosidase was purified from the culture supernatant of Streptococcus mutans Ingbritt and characterized. The molecular weight of the enzyme was 127,000 as determined by SDS-polyacrylamide gel electrophoresis. The enzyme was specific for levan which mainly consists of beta-(2,6)-linked D-fructose and was also able to hydrolyze inulin, sucrose and raffinose at the activities of 13, 9 and 5% of that hydrolyzing levan, respectively. The pH optima for levan, inulin and sucrose were approximately 5.5, 6.0 and 5.0, respectively. The enzyme was optimally reactive at 55 C for levan. The enzyme was inhibited by Fe3+, Hg2+ and Zn2+ and not by either anionic or non-ionic detergents. Paper chromatographic analysis revealed that the enzyme attacked levan by an exo-type mechanism.
authors.affiliation: Department of Oral Microbiology, Showa University School of Dentistry, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Igarashi
authors.forename: A
authors.initials: A
authors.lastname: Yamamoto
authors.forename: N
authors.initials: N
authors.lastname: Goto
mesh_terms: D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D013295:Streptococcus mutans / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D004791:Enzyme Inhibitors; D006026:Glycoside Hydrolases; C044118:fructan beta-fructosidase