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1989 Fiscal Year Final Research Report Summary

Studies on structure-function relationship of enzymes catalyzing asymmetric syntheses of Michael addition type.

Research Project

Project/Area Number 63470136
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field 物質生物化学
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

TOKUSHIGE Masanobu  Kyoto University, Faculty of Science, Professor, 理学部, 教授 (20025266)

Co-Investigator(Kenkyū-buntansha) YUNOTO Noboru  Kyoto University, Faculty of Science, Instructor, 理学部, 助手 (30200877)
Project Period (FY) 1988 – 1989
KeywordsMichael addition / Aspartase / Fumarase / Asymmetric synthesis / Sequence homology / Hybridization / Site-directed modification / Fe-S cluster
Research Abstract

In order to elucidate the structure-function characteristics of aspartases and fumarases, which catalyze asymmetric synthetic reactions of Michael addition type, enzymatic and genetic studies were carried out, and the following results were obtained.
1) Aspartase of Escherichiac coli, composed of 4-identical subunits was inactivated by chemical-modification with N-ethylmaleimide (NEM) and denatured in 4 M guanidine-HCl (GuHC1) in the presence of various ratio of the active enzyme. The denatured mixture was then renatured by dilution with dilute phosphate buffer, pH 7.4. The hybridized enzyxne exhibited the aspartase activity in proportion to the content of the unmodified subunit, indicating that as long as the quaternary structure is proper, the enzyme activity can be exhibited, even if some subunits are inactive.
2) Cysteind 430 of aspartase, which participates in the activation of the catalytic activity was genetically converted to tryptophan using synthetic oligonucleotides. Trp-430-containing aspartase exhibited 4 times higher enzyme activity at acidic pH, and the requirement for divalent metal ions was also increased.
3) Available-evidence suggests that E. colicells contain three fumarases, FUMA, FUMB, dnd FUMC. We purified a fumarase which required divalent ferrous ions for its activity. The purified enzyme was found to contain iron-S cluster like aconitase and was identified as a product of fumA. FUMC, which did not require ferrous ions was also purified to homogeneety.
4) Freviously we utilized aspartic beta-semialdehyde (ASA) as a kind of suicide substrate of aspartase. In order to extend this study, we established a rapid purification procedure for homoserine dehydrogenase of yeast, by which a large amount of ASA supply became possible.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Yumoto,N.&Tokushige,M.: "Characterization of multiple fumarase proteins in Escherichia coli." Biochem.Biophys.Res.Commun.,. 153. 1236-1243 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Imaishi,H.,Yumoto,N.&Tokushige,M.: "Preparation of active hybrid enzymes composed of the native and chemically inactivated aspartase subunits from Escherichia coli" Biotechnol.Appl.Biochem.,in press. (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Imaishi,H.,Yumoto,N.&Tokushige,M.: "Characterization of intermediate species during the molecular assembly of aspartase." Physiol.Chem.Phys.Med.NMR,in press.(1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yumoto,N.,Kawata,Y.,Noda,S.&Tokushige,M.: "Rapid purification and characterization of homoserine dehydrogenase from Saccharomyces cerevisiae.,submitted" Eur.J.Biochem.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Ueda,Y.,Yumoto,N.&Tokushige,M.: "Purification and Characterization of two types of fumarase from Escherichia coli.,submitted" J.Biol. Chem.

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳重正信: "UPバイオロジ-NO.70酵素のはたらき" 東京大学出版会, (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 徳重正信: "生命の化学最前線" さんえい出版, (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yumoto,N. & Tokushige,M.: "Characterization of multiple fumarase proteins in Escherichia coli." Biochem. Biophys. Res. Commun., 153, 1236-1243, 1988.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Imaishi,H., Yumoto,N., & Tokushige,M.: "Preparation of active hybrid enzymes composed of the native and chemically inactivated aspartase subunits from Escherichia coli." Biotechnol. Appl. Biochem. 1990.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Imaishi,H., Yumoto,N., & Tokushige,M.: "Characterization of intermediate species during the molecular assembly of aspartase." Physiol. Chem. Phys. Med. NMR, 1990.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yumoto,N., Kawata,Y., Noda,S., & Tokushige,M.: "Rapid purification and characterization of homoserine dehydrogenase from Saccharomyces cerevisiae." Eur. J. Biochem.,.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Ueda,Y., Yumoto,N., & Tokushige,M.: "Purification and characterization of two types of fumarase from Escherichia coli." J. Biol. Chem.,.

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-26  

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