Spectroscopic Studies on the Aggregates and the Dissociates Induced by Heating Soybean 11S Globulin in the Presence of N-Ethylmaleimide

Heating 11S globulin in the presence of Ν-ethylmaleimide (NEM) gave buffer-soluble aggregates and dissociates. The difference-second derivative absorption spectra indicated that the aggregates had larger internal hydrophobicity than 11S globulin, while that of the dissociates was conversely smaller. The protein’s fluorescence spectra indicated that, compared with 1 IS globulin, the wavelength of the fluorescence peak of the aggregates was hardly shifted, while that of the dissociates was red-shifted. The circular dichroism of the aggregates was similar to that of 11S globulin.These results suggest that the aggregates were formed with retention of the internal hydrophobic region of 11S globulin, while the dissociates released from 11S globulin were unfolded with increasing heating time.