AMINO-ACID GRAFTING OF BETA-LACTOGLOBULIN MEDIATED BY PHOSPHORUS OXYCHLORIDE

beta-Lactoglobulin was phosphorylated with 80 mot of POCl3/mol protein in the presence of triethylamine and amino acids or their esters adde d at a total molar excess of 6 mol base/mol POCl3. The extent of phosp horylation was reduced when the amino acids replaced triethylamine as the base. Arginine and lysine were grafted to protein molecules in amo unts proportional to the beta-lactoglobulin phosphorylation, while his tidine grafting was very weak. The electrophoretic patterns of the mod ified proteins showed increased negative charges, reduced isoionic poi nts and slight dimerization. The emulsifying properties of the modifie d proteins were improved.