Purification and characterization of a novel β-agarase from an alkalophilic bacterium, Alteromonas sp. E-1

Kotaro Kirimura, Noriyoshi Masuda, Yousuke Iwasaki, Hiroyuki Nakagawa, Reijiro Kobayashi, Shoji Usami

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    Abstract

    A novel β-agarase (EC 3.2.1.81) was purified from an agar-degrading alkalophilic bacterium, Alteromonas sp. E-1 isolated from the soil. This enzyme was obtained from a cell-free extract after sonication and purified 40.9-fold through treatment with streptomycin, ammonium sulfate fractionation and successive chromatography on anion-exchange and gel filtration columns. The molecular weight was estimated to be 82 kDa by SDS-polyacrylamide gel electrophoresis and 180 kDa by Superdex 200 gel filtration. The enzyme was inhibited by Mn2+, Cu2+, Fe2+, Zn2+ and Hg2+, and activated by K+, Na+ and EDTA, and its optimum pH and temperature for agarose degradation were 7.5 and 40°C, respectively. This ̄-agarase hydrolyzed agarose with rapid reduction of viscosity, and neoagarobiose [O-3,6-anhydro-α-L- galactopyranosyl(1→3)-D-galactose] was detected from the early stage of the reaction. Neoagarobiose as the final product was selectively released from agarose, neoagarohexaose and neoagarotetraose by the reaction with this β- agarase. This observation was different from that of other β-agarases which produced mixtures of neoagarobiose and neoagarotetraose as the final hydrolysis products. The N-terminal amino acid sequence of this β-agarase shows no homology to those of other β-agarases that were so far reported.

    Original languageEnglish
    Pages (from-to)436-441
    Number of pages6
    JournalJournal of Bioscience and Bioengineering
    Volume87
    Issue number4
    DOIs
    Publication statusPublished - 1999

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    Keywords

    • β-agarase
    • Alteromonas
    • Neoagarobiose
    • Neoagarooligosaccharide

    ASJC Scopus subject areas

    • Biotechnology
    • Bioengineering

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