Stability of immobilized thermolysin in organic solvents

Masamitsu Miyanaga, Michihiro Ohmori, Koreyoshi Imamura, Takaharu Sakiyama, Kazuhiro Nakanishi

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Various factors affecting the stability of thermolysin immobilized by cross-linking with glutaraldehyde were elucidated, particularly in the water- immiscible organic solvents such as ethyl acetate and tert-amyl alcohol. The main reason for enzyme inactivation in water-immiscible organic solvents was found to be autolysis in the water phase, which may surround the enzyme immobilized inside the support. By contrast, in water-miscible organic solvents thermal denaturation was the predominant cause of enzyme inactivation. Courses of inactivation were expressed by second-order kinetics in the initial stage, after which inactivation proceeded at a slower rate. The extent of autolysis was found to strongly depend on the kind of organic solvent, the water content, and type of support and these dependencies were explained by the difference in the amount and state of water inside the support. Thermolysin was immobilized onto Amberlite XAD-7 as a compact aggregate inside the support which may increase the stability of the enzyme. Finally, it was shown that the stability of the immobilized enzyme could be correlated with the logP value for water-miscible organic solvents and with the solubility of water for water-immiscible organic solvents.

Original languageEnglish
Pages (from-to)463-472
Number of pages10
JournalJournal of Bioscience and Bioengineering
Issue number4
Publication statusPublished - 1999


  • Autolysis
  • Immobilized enzyme
  • Inactivation kinetics
  • Organic solvent
  • Thermolysin

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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