Biochemical and crystallographic characterization of the starch branching enzyme I (BEI) from Oryza sativa L

Nhuan Thi Vu, Hiroaki Shimada, Yoshimitsu Kakuta, Takashi Nakashima, Hiroko Ida, Toshiro Omori, Aiko Nishi, Hikaru Satoh, Makoto Kimura

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Starch branching enzyme (SBE) catalyzes the cleavage of α-1.4-linkages and the subsequent transfer of α-1.4 glucan to form an α-1.6 branch point in amylopectin. We overproduced rice branching enzyme I (BEI) in Escherichia coli cells, and the resulting enzyme (rBEI) was characterized with respect to biochemical and crystallographic properties. Specific activities were calculated to be 20.8 units/mg and 2.5 units/mg respectively when amylose and amylopectin were used as substrates. Site-directed mutations of Tyr235, Asp270, His275, Arg342, Asp344, Glu399, and His467 conserved in the α-amylase family enzymes drastically reduced catalytic activity of rBEI. This result suggests that the structures of BEI and the other α-amylase family enzymes are similar and that they share common catalytic mechanisms. Crystals of rBEI were grown under appropriate conditions and the crystals diffracted to a resolution of 3.0 Å on a synchrotron X-ray source.

Original languageEnglish
Pages (from-to)2858-2866
Number of pages9
JournalBioscience, Biotechnology and Biochemistry
Volume72
Issue number11
DOIs
Publication statusPublished - Dec 1 2008

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Analytical Chemistry
  • Biochemistry
  • Applied Microbiology and Biotechnology
  • Molecular Biology
  • Organic Chemistry

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