Heterogeneity of caprine kappa-casein macropeptide.
The heterogeneity of caprine caseinmacropeptide (CMP) was determined by means of treatments with neuraminidase and acid phosphatase and analyses by anion exchange FPLC and reversed-phase (RP)-HPLC, with on-line and off-line electrospray ionization mass spectrometry. The main CMP components were two non-glycosylated and di-phosphorylated forms, as well as two other mono-phosphorylated species, each corresponding to a genetic variant of caprine kappa-casein due to the silent substitution Ile/Val at position 119. Asialo-aglyco mono- and di-phosphorylated forms were found in the ratios 8-14% and 86-92%, respectively. Approximately 36% of caprine CMP was glycosylated. Based on the obtained molecular masses, the occurrence of tri-, di- and monosaccharide-containing di-phosphorylated CMP are reported, assuming that N-acetylgalactosamine, galactose, N-acetyl and N-glycolylneuraminic acids would constitute the main monosaccharides of caprine CMP. CMP microheterogeneity due to the genetic polymorphism was also observed in the glycosylated forms.
Moreno
F J
FJ
Instituto de Fermentaciones Industriales (CSIC), Madrid, Spain.
Recio
I
I
Olano
A
A
López-Fandiño
R
R
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D002364:Caseins / Q000737:chemistry* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods / Q000662:veterinary; D002852:Chromatography, Ion Exchange / Q000379:methods / Q000662:veterinary; D005260:Female; D006031:Glycosylation; D006041:Goats / Q000502:physiology; D013058:Mass Spectrometry / Q000379:methods / Q000662:veterinary; D008892:Milk / Q000737:chemistry* / Q000378:metabolism; D009439:Neuraminidase / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D010766:Phosphorylation; D011110:Polymorphism, Genetic
D002364:Caseins; D010455:Peptides; D000135:Acid Phosphatase; D009439:Neuraminidase