Kinetic parameters of two rice α-amylase isozymes for oligosaccharide degradation

Masaaki Terashima, Norio Hayashi, Bruce R. Thomas, Raymond L. Rodriguez, Shigeo Katoh

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The rice α-amylase isozymes Amy1A and Amy3D have distinct kinetic parameters and product profiles. For Amy3D, Michaelis constants (Km) decrease, and molecular activities (kcat) increase with the chain length of the substrates from maltose to maltoheptaose. Although Amy1A has a lower Km than Amy3D, the kcat of Amy1A was much lower than that of Amy3D. Amy1A produces only negligible amounts of glucose, while Amy3D produces glucose as a major product. Glucose regulates the expression of a number of genes in developing seedlings, so Amy3D may have a unique regulatory role in control of seedling development.

Original languageEnglish (US)
Pages (from-to)9-14
Number of pages6
JournalPlant Science
Issue number1
StatePublished - 1996


  • α-amylase
  • Action pattern
  • Carbon metabolite signal
  • Kinetic constant
  • Oligosaccharide
  • Rice

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Biotechnology


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