FACILE CHARACTERIZATION OF THE SPECTRA OF CIS AND TRANS PHOTOISOMERS IN A MIXTURE OF ACYL-ENZYMES BY RAMAN DIFFERENCE SPECTROSCOPY

Raman difference spectroscopy is used to provide the spectra of both t he cis and trans forms of acryloyl-based acyl enzymes from a mixture w ithout resorting to purification. A mixture of cis and trans, about th e-C=CC(=O) ethylenic linkage, is generated photochemically and by subt racting the Raman spectrum of the mixture from the spectrum of the pur e trans form prior to photochemical irradiation, Raman peaks of the tr ans acyl-enzyme appear as ''negative'' features and of the cis form ap pear as ''positive'' features. No operator intervention is required to scale the spectra for subtraction, and thus information on the relati ve Raman scattering efficiencies of the cis and trans isomers can be o btained immediately from the data. Results for 5-methylthienylacryloyl chymotrypsin confirm earlier data for the purified cis and trans form s and data for cis indoleacryloyl chymotrypsin are presented for the f irst time.