Kinetic analysis for synthesis of a dipeptide precursor using an immobilized enzyme in water-immiscible organic solvents

Masamitsu Miyanaga, Koreyoshi Imamura, Takaharu Sakiyama, Kazuhiro Nakanishi

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

N-(Benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methyl ester (Z-AspPheOMe), a precursor of the synthetic sweetener aspartame, was synthesized, using thermolysin immobilized onto Amberlite XAD-7, both in ethyl acetate and in tert-amyl alcohol. The initial rates for synthesis of Z-AspPheOMe in the organic solvents were predicted on the basis of a model proposed for an aqueous/organic biphasic reaction and compared with the experimentally observed substrate concentration dependencies. The experimental synthetic rates using the enzyme immobilized at a high enzyme concentration were lower than the calculated ones over a wide range of the substrate concentration. It was suggested as a reason for this discrepancy that the enzyme molecules form compact aggregates and those existing inside the aggregates cannot be utilized for reaction. The experimental results with the enzyme immobilized at a low concentration in ethyl acetate coincided well with the calculated ones. On the other hand, when tert-amyl alcohol was used, the experimental results were different in tendency irrespective of the amount of enzyme loaded, probably due to the fact that a distinct water phase does not exist around the enzyme aggregates inside the support.

Original languageEnglish
Pages (from-to)112-114
Number of pages3
JournalJournal of Bioscience and Bioengineering
Volume90
Issue number1
DOIs
Publication statusPublished - Jan 1 2000

Keywords

  • Aspartame
  • Dipeptide
  • Enzymatic synthesis
  • Immobilized enzyme
  • Organic solvent
  • Thermolysin

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology

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