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Fluorescence and CD spectroscopic analysis of the α‐chymotrypsin stabilization by the ionic liquid, 1‐ethyl‐3‐methylimidazolium bis[(trifluoromethyl)sulfonyl]amide
Author(s) -
De Diego Teresa,
Lozano Pedro,
Gmouh Said,
Vaultier Michel,
Iborra José L.
Publication year - 2004
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.20330
Subject(s) - ionic liquid , chemistry , sulfonyl , circular dichroism , sorbitol , thermal stability , trifluoromethyl , differential scanning calorimetry , chymotrypsin , fluorescence , crystallography , organic chemistry , enzyme , alkyl , catalysis , thermodynamics , physics , trypsin , quantum mechanics
The stability of α‐chymotrypsin in the ionic liquid, 1‐ethyl‐3‐methyl‐imidizolium bis[(trifluoromethyl)sulfonyl]amide ([emim][NTf 2 ]), was studied at 30 and 50°C and compared with the stability in other liquid media, such as water, 3 M sorbitol, and 1‐propanol. The kinetic analysis of the enzyme stability pointed to the clear denaturative effect of 1‐propanol, while both 3 M sorbitol and [emim][NTf 2 ] displayed a strong stabilizing power. For the first time, it is shown that enzyme stabilization by ionic liquids seems to be related to the associated structural changes of the protein that can be observed by differential scanning calorimetry (DSC) and fluorescence and circular dichroism (CD). The [emim][NTf 2 ] enhanced both the melting temperature and heat capacity of the enzyme compared to the other media assayed. The fluorescence spectra clearly showed the ability of [emim][NTf 2 ] to compact the native structural conformation of α‐chymotrypsin, preventing the usual thermal unfolding which occurs in other media. Changes in the secondary structure of this β/β protein, as quantified by the CD spectra, pointed to the great enhancement (up 40% with respect to that in water) of β‐strands in the presence of the ionic liquid, which reflects its stabilization power. © 2004 Wiley Periodicals, Inc.