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Spectrophotometric assay for protease activity in ionic liquids using chromogenic substrates
Kazunori Nakashima1, Tatsuo Maruyama, Noriho Kamiya
1Department of Applied Chemistry, Graduate School of Engineering, and Center for Future Chemistry, Kyushu University, Fukuoka 819-0395, Japan.
Analytical Biochemistry
|December 15, 2007
Summary
A new spectrophotometric assay allows easy, real-time evaluation of protease activity in ionic liquids. This method uses modified enzymes and chromogenic substrates for UV-Vis detection, simplifying enzymatic analysis in novel solvents.
Area of Science:
- Biochemistry
- Analytical Chemistry
- Green Chemistry
Background:
- Ionic liquids (ILs) offer unique solvent properties but pose challenges for enzymatic assays.
- Traditional methods for enzyme activity analysis are often incompatible with ILs.
- Developing robust assays for enzyme function in ILs is crucial for biocatalysis research.
Purpose of the Study:
- To develop a novel spectrophotometric assay for evaluating protease activity in ionic liquids.
- To enable real-time monitoring of enzymatic reactions within ILs.
- To demonstrate the assay's utility in kinetic analysis and enzyme specificity studies.
Main Methods:
- Enzyme modification with comb-shaped poly(ethylene glycol) (PM(13)) for solubility in ILs.
- Utilizing chromogenic substrates (p-nitroaniline-derivatized) for spectrophotometric detection.
- Performing protease-catalyzed alcoholysis and quantifying released p-nitroaniline via UV-Vis spectrophotometry.
Main Results:
- Successful development of a real-time spectrophotometric assay for protease activity in ILs.
- Demonstrated ease of use without product separation.
- Kinetic analysis of subtilisin in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][Tf(2)N]) was performed.
- Substrate specificity of subtilisin and alpha-chymotrypsin was retained in the IL.
Conclusions:
- The novel assay provides a straightforward method for assessing protease activity in ionic liquids.
- The assay is adaptable for various enzymes and chromogenic substrates.
- This facilitates the study and application of enzymes in IL-based systems.
