Peptidomic approach based on combined capillary isoelectric focusing and mass spectrometry for the characterization of the plasmin primary products from bovine and water buffalo beta-casein.
The main peptides produced by hydrolysis of water buffalo beta-casein with plasmin were characterized by capillary electrophoresis and mass spectrometry and compared with their bovine homologous. A novel breakdown product arising from the hydrolysis of water buffalo beta-casein, originated by the presence of a plasmin-sensitive Lys bond at position 68 was identified, which was not present in bovine beta-casein. On the basis of this evidence, an improved procedure for the detection and the differentiation of the products of plasmin hydrolysis of bovine and water buffalo beta-casein by capillary isoelectric focusing was set-up. In the experimental conditions, the gamma-casein from the two species was efficiently separated. Comparison of the capillary electropherograms with those obtained by ultra-thin-layer isoelectric focusing, the reference method for routine analysis of plasmin digests of casein, suggests that capillary electrophoresis isoelectric focusing may constitute a successful alternative to the traditional slab gel electrophoresis analysis of plasmin digests of casein either for basic structural studies or for applications in the quality assessment of dairy products.
Somma
Andrea
A
Dipartimento di Scienza degli Alimenti, University of Naples Federico II, Parco Gussone, Portici I-80055, Italy.
Ferranti
Pasquale
P
Addeo
Francesco
F
Mauriello
Rosalba
R
Chianese
Lina
L
D000595:Amino Acid Sequence; D000818:Animals; D002020:Buffaloes / Q000378:metabolism*; D002364:Caseins / Q000032:analysis*; D002417:Cattle; D002852:Chromatography, Ion Exchange; D005260:Female; D005341:Fibrinolysin / Q000032:analysis*; D006868:Hydrolysis; D007525:Isoelectric Focusing; D013058:Mass Spectrometry; D008892:Milk / Q000737:chemistry*; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D002364:Caseins; D010455:Peptides; D005341:Fibrinolysin