Acetylation 이 포도당과 함께 저장중에 있는 콩단백질의 기능에 미치는 영향

학위논문(석사) - 한국과학기술원 : 생물공학과, 1986.2, [ i, 43 p. ]Alteration of the chemical structure of proteins can be caused by deteriorative reactions such as Maillard reaction and by modification with chemical reagents intentionally done to alter the properties of the proteins. Acetylated soybean protein isolates (0\%, 25\%, 35\%, 55\%, 80\%) were incubated with glucose to induce Maillard reaction. Acetylation improved water sorption, fat binding, foam formation, and emulsion activity of the protein, but depressed browning and trypsin digestion. Storage caused Maillard reaction to occur, and such functionalities as water sorption, foam formation, and trypsin digestion were deterirated, but fat adsorption and emulsion activity were improved. Thus acetylation prevented deterioration of certain functional characteristics that occurred during storage, besides causing functional characteristics to be improved on its own.한국과학기술원 : 생물공학과

아세틸화가 대두 glycinin 의 물리화학적 특성과 기능적 특성에 미치는 영향에 관한 연구

학위논문(박사) - 한국과학기술원 : 생물공학과, 1989.8, [ x, 133 p. ]Acetylation of $\varepsilon$-amino groups of lysine residues changed conformation of glycinin isolated from soy bean, the extent of which depended upon the degree of modification. Soy glycinin with lysine residue modifications of 0\%, 28\%, 65\%, 85\%, and 95\% were used for the experiment. Accessibility of tyrosine and tryptophan residues, which were shown to increase as modification percent increased, were detected using uv absorption spectra and fluorescence spectra, respectively. Surface hydrophobicity was found to increase more than times over native glycinin when lysine residues were excessively modified to above 95\%. Masking of charged lysine residues, exposure of hydrophobic interior, and subunit dissociation have contributed to the increase. Enthalpy, as obtained from differential scanning calorimetry, dropped from 3.6 cal/g native protein to 0 cal/g protein when lysine residues were acetylated above 65\%, implicating complete denaturation. The hydrolytic rates, using $\alpha$-chymotrypsin, increased initially, then decreased at more than 65\% lysine modification. Effect of the acetylation on turbidity of protein was investigated using samples of 0\%, 65\%, and 90\% acetylation. Turbidity of acetylated glycinin decreased and isoelectric point shifted to acidic region. Salts (NaCl, $CaCl_2$) were found to hardly affect turbidity of acetylated glycinin in contrast to native one. Sodium chloride depressed turbidity of native protein while that of 90\% modified sample was scarcely changed. Calcium chloride dramatically increased turbidity of native protein at above pH 7, while that of 90\% modified glycinin was hardly affected. Heat stability of glycinin was found to increase by acetylation. Conglycinin affected little on turbidity of acetlylated glycinin in contrast to the native protein. Emulsfying properties of acetylated glycinin was also checked using samples of 0\%, 45\%, and 90\% modification. At oil to protein solution ratio of 2.5:7, pH 7.6, 90\%...한국과학기술원 : 생물공학과