SPECTROSCOPIC STUDIES ON THE CONFORMATION OF NATIVE and DENATURED GLYCININ

Optical rotatory dispersion (ORD) studies and infrared spectra in deuterium oxide indicate that native glycinin exhibits mainly a β‐conformation structure. Ultraviolet difference spectra showed that urea ami guanidine hydrochloride at increasing concentrations cause progressive exposure of tyrosine and tryptophan residues. Ultraviolet difference spectroscopy was also used in following the course of acid‐induced denaturation of glycinin. It was observed that acid denaturation starts approximately at pH 3.50 reaching a maximum at pH 2.0. Data obtained by solvent perturbation of native glycinin using perturbants exhibiting mean diameters of 2.0, 4.4, and 7.2 A indicate that approximately 34 to 37 residues (45%of the total) are accessible to these perturbants whereas the accessibility of tryptophan residues is decreased with increasing mean diameters of the perturbant.