Enzymatic properties of a novel liquefying α-amylase from an alkaliphilic Bacillus isolate and entire nucleotide and amino acid sequences

Kazuaki Igarashi, Yuji Hatada, Hiroshi Hagihara, Katsuhisa Saeki, Mikio Takaiwa, Takaaki Uemura, Katsutoshi Ara, Katsuya Ozaki, Shuji Kawai, Tohru Kobayashi, Susumu Ito

研究成果: Article査読

100 被引用数 (Scopus)

抄録

A novel liquefying α-amylase (LAMY) was found in cultures of an alkaliphilic Bacillus isolate, KSM-1378. The specific activity of purified LAMY was approximately 5,000 U mg of protein-1, a value two- to fivefold greater between pH 5 and 10 than that of an industrial, thermostable Bacillus licheniformis enzyme. The enzyme had a pH optimum of 8.0 to 8.5 and displayed maximum activity at 55°C. The molecular mass deduced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis was approximately 53 kDa, and the apparent isoelectric point was around pH 9. This enzyme efficiently hydrolyzed various carbohydrates to yield maltotriose, maltopentaose, maltohexaose, and maltose as major end products after completion of the reaction. Maltooligosaccharides in the maltose-to-maltopentaose range were unhydrolyzable by the enzyme. The structural gene for LAMY contained a single open reading frame 1,548 bp in length, corresponding to 516 amino acids that included a signal peptide of 31 amino acids. The calculated molecular mass of the extracellular mature enzyme was 55,391 Da. LAMY exhibited relatively low amino acid identity to other liquefying amylases, such as the enzymes from B. licheniformis (68.9%), Bacillus amyloliquefaciens (66.7%), and Bacillus stearothermophilus (68.6%). The four conserved regions, designated I, II, III, and IV, and the putative catalytic triad were found in the deduced amino acid sequence of LAMY. Essentially, the sequence of LAMY was consistent with the tertiary structures of reported amylolytic enzymes, which are composed of domains A, B, and C and which include the well-known (α/β)8 barrel motif in domain A.

本文言語English
ページ(範囲)3282-3289
ページ数8
ジャーナルApplied and Environmental Microbiology
64
9
DOI
出版ステータスPublished - 1998
外部発表はい

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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