低イオン強度下での大豆グリシニン蛋白質の加熱変性 : 凝集物及び解離物の分光学的及び電気泳動的研究

概要

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Heating glycinin at the low ionic strength caused changes in the intensities of the second derivative absorption spectra, but scarcely affected the positions of the peaks and troughs. The spectra indicated that half of tyrosine residues buried in native glycinin was exposed by heating, but tryptophan residues were hardly done. Tryptophanyl fluorescence spectra gave the same information as that obtained by the ultra-violet absorption spectra. Gel filtration of thermal products gave buffer-soluble aggregates as a major component and dissociates. Electrophoresis indicated that the former and the latter consisted of polymerized subunits through disulfide bond, and a monomer and oligomer of acidic subunit, respectively. Difference-derivative absorption spectra indicated that internal hydrophobicity of aggregates was larger than native glycinin, while that of dissociates was conversely smaller. These results suggest that the aggregates were formed with retention of the internal hydrophobic region of glycinin, while the released dissociates were unfolded. Soluble aggregates formed by heating at 0.01 ionic strength would be the soluble macroaggregates before formation of gel network.