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EFFECTS OF ACETYLATION ON PHYSICOCHEMICAL PROPERTIES OF J1S SOY PROTEIN
Author(s) -
KIM KANG SUNG,
RHEE JOON SHICK
Publication year - 1989
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.1989.tb00393.x
Subject(s) - lysine , chemistry , tryptophan , acetylation , tyrosine , denaturation (fissile materials) , soy protein , differential scanning calorimetry , residue (chemistry) , chymotrypsin , chemical modification , biochemistry , chromatography , amino acid , trypsin , enzyme , nuclear chemistry , physics , gene , thermodynamics
Acetylation of ε‐amino groups of lysine residues changed conformation of glycinin isolated from soybean, 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 two 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 should have contributed to the increase. Enthalpy, as obtained from differential scanning calorimetry, dropped from 3.6 callg native protein to 0 callg protein, when lysine residues were acetylated above 65%. implicating complete denaturation. The hydrolytic rates, using α‐chymotrypsin, increased initially, then decreased at more than 65% lysine modification.