Peptic proteolysis of esterified β-casein and β-lactoglobulin

Moderate esterification induces slight secondary structure changes in two major milk proteins, β-lactoglobulin and β-casein. Esterification of β-lactoglobulin prompts its tertiary structure‘melting′, opening it to peptic cleavage. Twenty-two new cleavage sites were characterised in β-lactoglobulin and five in β-casein. Some of them are due to esterification-improved peptide bond accessibility, some to the bias of pepsin specificity by glutamate and aspartate esters. The resulting fragmentation yields original and partially amphiphilic peptide populations.