Effect of Dephosphorylation on Donkey Milk Caseins

Donkey milk caseins display great microheterogeneity by two-dimensional electrophoresis (2-DE), probably because of a variable degree of phosphorylation and/or alternative splicing phenomena. In this work, we have investigated the complexity of the donkey milk caseins: The whole casein fraction was subjected to treatment with calf intestinal alkaline phosphatase to achieve dephosphorylation. The obtained apo forms were analyzed by 2-DE and compared with whole donkey caseins. As a result, donkey milk β-casein and its splicing variants are present as different phosphorylated isoforms, whereas α S1-casein displays several isoforms that are derived from both phosphorylation and glycosylation phenomena