Phosphopeptides from Grana Padano cheese: nature, origin and changes during ripening.
Casein phosphopeptides (CPP) which develop in Grana Padano cheese at different ages were isolated by precipitation with Ba2+ and analysed by HPLC. Profiles were complex throughout the period between 4 and 38 months. CPP in a cheese sample 14 months old were identified by a combination of fast atom bombardment-mass spectrometry and Edman degradation. They were found to consist of a mixture of components derived from three parent peptides, beta-CNf(7-28)4P, alpha s1-CNf(61-79)4P and alpha s2-CNf(7-21)4P. In total, 45 phosphopeptides were identified: 24 from beta-CN, 16 from alpha s1-CN and 5 from alpha s2-CN. The presence of aminopeptidase activity during cheese ripening was deduced from the presence of a number of CPP of different lengths with the loss of one or more residues from the N-terminus. The longest had C-terminal lysine and seemed to be progressively hydrolysed by carboxypeptidases A and B to shorter peptides. CPP in cheese appeared to be shortened plasmin-mediated products. Moreover, those most resistant to further hydrolysis contained at least three closely located phosphoserine residues. The anticariogenic activity of CPP is also discussed.
Ferranti
P
P
Dipartimento di Scienza degli Alimenti, Facoltà di Agraria, Università degli Studi di Napoli Federico II, Portici, Italia.
Barone
F
F
Chianese
L
L
Addeo
F
F
Scaloni
A
A
Pellegrino
L
L
Resmini
P
P
D000595:Amino Acid Sequence; D001464:Barium; D002268:Carboxypeptidases / Q000378:metabolism; D002364:Caseins / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D002611:Cheese / Q000032:analysis*; D011232:Chemical Precipitation; D002851:Chromatography, High Pressure Liquid; D005341:Fibrinolysin / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008239:Lysine / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D010748:Phosphopeptides / Q000032:analysis*; D010768:Phosphoserine / Q000032:analysis / Q000378:metabolism; D012995:Solubility; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism
D002364:Caseins; D010446:Peptide Fragments; D010748:Phosphopeptides; D010768:Phosphoserine; D001464:Barium; D002268:Carboxypeptidases; D014357:Trypsin; D005341:Fibrinolysin; D008239:Lysine