A study of interaction between α-chymotrypsin and 18-crown-6 in organic solvents by Raman spectroscopy

Conformational changes of alpha -chymotrypsin caused by its interactions with organic solvents and 18-crown-6 were studied by Raman spectroscopy. The IR spectra of a-chymotrypsin lyophilized in the presence and absence of 18-crown-6, in the solid state, in acetonitrile and cyclohexane, and at various relative enzyme and crown molar concentrations were recorded. Tris(hydroxymethyl)aminomethane and its complexes with 18-crown-6 were used as chemical models to study interaction between the amino groups of the protein and the crown. The conformation of enzyme molecules in water was found to be drastically different from that in the "dry" sample and in organic solvents. The influence of the crown and solvents on conformation-sensitive enzyme bands is discussed.