MOLTEN GLOBULE STATE OF PROTEIN MOLECULES IN HEAT-INDUCED TRANSPARENTFOOD GELS

The microstructures of transparent gels from ovalbumin, hen egg white lysozyme, and bovine serum albumin were examined by high-resolution sc anning electron microscopy. Three transparent gel matrices were clearl y found to be composed of a common structural unit in which heat-denat ured molecules formed fine networks of linear aggregates. The molecula r conformation of heat-denatured proteins in linear aggregates produce d after heat treatment in the absence of salt was studied by measuring circular dichroism spectra, intrinsic tryptophan fluorescence, and ad sorption of the dye 1-anilinonaphthalene-8-sulfonate. These experiment s showed that all three heat-denatured proteins did not take on a rand om-coiled state but rather remained partially folded, with some hydrop hobic regions becoming exposed to the solvent environment. This confor mation could thus be categorized as the ''molten globule'' state.