Open AccessPurification and Characterization of 2,6-β- d -Fructan 6-Levanbiohydrolase from Streptomyces exfoliatus F3-2
Author(s) -
Katsuichi Saito,
Kazuya Kondo,
Ichiro Kojima,
Atsushi Yokota,
Fusao Tomita
Publication year - 2000
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.66.1.252-256.2000
Subject(s) - fructan , enzyme , isoelectric point , biochemistry , polyacrylamide gel electrophoresis , chemistry , gel electrophoresis , molecular mass , enzyme assay , hydrolysis , isoelectric focusing , chromatography , fructose
Streptomyces exfoliatus F3-2 produced an extracellular enzyme that converted levan, a β-2,6-linked fructan, into levanbiose. The enzyme was purified 50-fold from culture supernatant to give a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights of this enzyme were 54,000 by SDS-PAGE and 60,000 by gel filtration, suggesting the monomeric structure of the enzyme. The isoelectric point of the enzyme was determined to be 4.7. The optimal pH and temperature of the enzyme for levan degradation were pH 5.5 and 60°C, respectively. The enzyme was stable in the pH range 3.5 to 8.0 and also up to 50°C. The enzyme gave levanbiose as a major degradation product from levan in an exo-acting manner. It was also found that this enzyme catalyzed hydrolysis of such fructooligosaccharides as 1-kestose, nystose, and 1-fructosylnystose by liberating fructose. Thus, this enzyme appeared to hydrolyze not only β-2,6-linkage of levan, but also β-2,1-linkage of fructooligosaccharides. From these data, the enzyme fromS. exfoliatus F3-2 was identified as a novel 2,6-β-d -fructan 6-levanbiohydrolase (EC3.2.1.64 ).