Characterization of rice α-amylase isozymes expressed by Saccharomyces cerevisiae

M. Terashima, S. Katoh, B. R. Thomas, R. L. Rodriguez

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Two rice α-amylase isozymes, Amy1A and Amy3D, were produced by secretion from genetically engineered strains of Saccharomyces cerevisiae. They have distinct differences in enzymatic characteristics that can be related to the physiology of the germinating rice seed. The rice isozymes were purified with immunoaffinity chromatography. The pH optima for Amy3D (pH optimum 5.5) and Amy1A (pH optimum 4.2) correlate with the pH of the endosperm tissue at the times in rice seedling development when these isozymes are produced. Amy3D showed 10-14 times higher reactivity to oligosaccharides than Amy1A. Amy1A, on the other hand, showed higher reactivity to soluble starch and starch granules than Amy3D. These results suggest that the isozyme Amy3D, which is expressed at an early stage of germination, produces sugars from soluble starch during the early stage of seed germination and that the isozyme Amy1A works to initiate hydrolysis of the starch granules.

Original languageEnglish (US)
Pages (from-to)1050-1055
Number of pages6
JournalApplied Microbiology and Biotechnology
Issue number6
StatePublished - 1995

ASJC Scopus subject areas

  • Biotechnology
  • Microbiology
  • Bioengineering


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