[A quantitative method for evaluating the structure and conformational stability of proteins by second derivative UV-spectroscopy].

A quantitative method is suggested for estimating the structure and conformational stability of proteins based on the individual absorbance of Tyr residues in the second derivative UV spectra. Subtilisins Carlsberg, BPN' and 72 were chosen as the model proteins. The values of the increase of the Tyr absorption at 282.3 nm upon the total denaturation of the proteins made it possible to calculate the number of the exposed and "buried" tyrosine residues in the native proteins. A mathematical model of spectrum changes during the transition of Tyr residues from the "buried" to exposed form is suggested. The method is useful for the determination of the denaturation constants of proteins bearing "buried" tyrosine residues.