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

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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)


A novel β-agarase (EC 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
Issue number4
Publication statusPublished - 1999 Jan 1


  • Alteromonas
  • Neoagarobiose
  • Neoagarooligosaccharide
  • β-agarase

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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