ABSTRACTChemical modifications of tyrosine residues in κ‐casein were carried out to study their role in Ca‐αS1‐caseinate stabilization. In accord with Woychik and Wondolowski (1969), the stabilizing ability decreased on nitration with tetranitromethane. Electrophoretic patterns showed aggregation of the modified κ‐casein when 8 polyacrylamide gel was used at pH 8.6, whereas the casein migrated faster than the unmodified casein in 1.2 agarose gel suggesting increased negativity on casein malecules upon nitration. However, O‐acetylation with N‐acetylimidazole, after protecting SH and amino groups, did not cause any significant differences from the control κ‐casein in stabilizing ability or in electrophoretic patterns. Therefore, tyrosine residues are not essential for the stabilizing ab
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