Spectrophotometric assay for protease activity in ionic liquids using chromogenic substrates

Kazunori Nakashima, Tatsuo Maruyama, Noriho Kamiya, Masahiro Goto

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

A new spectrophotometric assay has been developed to evaluate protease activity in ionic liquids (ILs). The assay consists of two strategies to enable real-time spectrometric analysis of enzymatic reaction in ILs. First, enzymes are modified with a comb-shaped poly(ethylene glycol), PM13, to obtain a transparent enzyme solution in IL. Second, a chromogenic substrate is used to follow the enzymatic reaction in IL. p-Nitroaniline-derivatized substrates are subjected to protease-catalyzed alcoholysis to release chromogenic p-nitroaniline that can be quantitatively detected by a UV-Vis spectrophotometer. By using this method, we can evaluate protease activity in ILs quite easily without separation of products from the reaction mixture. The availability of the novel assay system was demonstrated in a kinetic analysis of subtilisin-catalyzed reaction in the IL 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][Tf2N]) under different reaction conditions. Because two different serine proteases, subtilisin and α-chymotrypsin, substantially retained its original substrate specificity in the IL, the assay can be extended to other enzymes by using suitable chromogenic substrates.

Original languageEnglish
Pages (from-to)285-290
Number of pages6
JournalAnalytical Biochemistry
Volume374
Issue number2
DOIs
Publication statusPublished - Mar 15 2008

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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