| heal.abstract |
Individual milk samples taken from goats of the Skopelos breed of Greece were analyzed by RP-HPLC using as standards the casein fraction of milks of known genotypes. Milk samples with particular characteristics with respect to the casein fraction were further analyzed by IEF and RP-HPLC/ESI-MS. The mean total protein content (36.7 ± 2.6 g·L-1) and the mean casein content (29.7 ± 2.3 g·-1) were high. The same was true for the αs1-cn fraction, which was 21.8% of the total en fraction, whereas the β-cn percentage of total en was 43.8%. The respective values for αs2-cn and κ-cn were 13.7% and 13.8%. These quantitative characteristics were consistent with the predominance of the strong αs1-cn variants B3, B4 and As/B1. In all samples analyzed by RP-HPLC/ ESI-MS the deleted form differing from the respective complete form by Gln78 was found at different levels of phosphorylation, with the exception of variants F and D/G. The most frequent αs2-cn variant was by far variant A followed by variants C and F, whereas compositional data implied the existence of a null allele. The detected β-cn forms were variants A and C in similar frequencies. Variant D (formerly B) of κ-cn predominated and the rare variant G was found. Different phosphorylation types of each casein variant and the characteristics of whey proteins were also determined. © INRA. |
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