PHOSPHORYLATION OF BETA-LACTOGLOBULIN UNDER MILD CONDITIONS

beta-Lactoglobulin was phosphorylated with different molar ratios of P OCl3/protein (20, 40, and 80) in the presence of either triethylamine or hexylamine (6 mol of base/mol of POCl3) in aqueous conditions. Urea -PAGE, SDS-PAGE, and isofocusing patterns showed increasing negative c harges and little cross-linking on beta-lactoglobulin molecule. The ci rcular dichroism spectra showed that phosphorylation has disordered th e secondary structure of beta-lactoglobulin. The phosphorylation-induc ed structural and electrostatic changes have displaced modified beta-l actoglobulin solubility minima toward lower values.