Phosphopeptides from Comte cheese: nature and origin

Thirteen low-molecular-weight phosphopeptides were isolated from the water-soluble fraction of Comte cheese. The sample was fractionated and purified by gel permeation chromatography and reverse-phase HPLC. The peptide sequences were identified by Edman degradation and primary molecular structure was confirmed by mass spectrometry. The different peptides purified correspond to fragments of the sequence Val13-Lys 28 of beta-casein and of the sequence Glu 5-Lys 21 of alpha(s2)-casein. These fragments probably originated from an initial proteolysis of the two caseins by plasmin, followed by further endopeptidase aminopeptidase and, possibly, carboxypeptidase digestions. Partial dephosphorylation of some beta-casein fragments was observed. These peptides probably influence the flavor profile of comte cheese