Fluorescence Spectroscopic Study of α-Chymotrypsin as Relevant to Catalytic Activity in Aqueous-Organic Media

Article abstract of DOI:10.1246/bcsj.66.1176

The effects of the composition of aqueous-organic mixed solvents on steady state fluorescence emission of α-chymotrypsin were investigated.In all the solvent systems, maximum wavelength of fluorescence emission shifted initially to higher wavelength and then to lower wavelength by increasing water content in organic solvents.The results were interpreted in terms of the changes in microenvironment of tryptophan residues in the enzyme due to conformational modification of the enzyme.The maximoum emission wavelength of chymotrypsin is well correlated to its catalytic activity for the hydrolysis of N-acetyl-L-tyrosine ethyl ester.Activity of chymotrypsin decreased or it was totally inhibited at solvent compositions which give long emission wavelength of the enzyme.The results suggest that the fluorescence spectroscopy may be useful for detection of conformational chnges and alternation of catalytic activity of the enzyme.