Para-K-casein

Figure 3.18. Elution pattern for a 250-mg sample of reduced and alkylated acid casein from DEAE-cellulose with NaCl gradient in buffer containing 6.6 M urea. Fraction (1), minor /3-caseins and para-K-casein-like material (2) K-casein and some /3-casein-1 P (f 29-209) (3) major /3-casein (4) as-caseins. (From Rose et al. 1969 Yaguchi and Rose 1971. Reprinted with permission of the American Dairy Science Association.)...

Cation-exchange columns have been used effectively by some investigators for the fractionation of casein (Annan and Manson 1969 Kim et al 1969 Kopfler et al. 1969 Snoeren et al. 1977 Saito et al 1979). Sulfoethyl-Sephadex was used by Annan and Manson (1969) with formate buffer to fractionate the as-casein complex. Cellulose phosphate, carboxyl-methyl-cellulose (CMC), potassium-K-carrageenan, and sodium Amberlite CG50 columns have also been used to fractionate the caseins (Kim et al. 1969 Kopfler et al. 1969 Snoeren et al 1977). A batch method for the preparation of para-K-casein from rennin-treated whole casein has been developed with CMC Sephadex (Saito et al. 1979). 

Jolles, J., Schoentgen, F Alais, C., Fiat, A.-M. and Joll6s, P 1972A. Studies on the primary structure of cow K-casein. Structural features of para-K-casein N-terminal sequence of K-casein-glycopeptides studied with a sequencer. Helv. Chim. Acta 55, 2872-2883. 

Chymosin, the principal proteinase of calf rennet, preferentially hydrolyzes the Phe105-Met10 bond to produce the para-K-casein fragment (f 1—105), which is the same whatever the degree of phosphorylation or glycosylation, and the macropeptide fragment (fl 06-169),... 

The primary phase of rennet action may be monitored by measuring the formation of either product, i.e. para-ic-casein or the GMP. Para-K-casein may be measured by SDS-polyacrylamide gel electrophoresis (PAGE),... 

MiraUes, B., Rothbaner, V., Manso, M., Amigo, 1., Krause, I., and Ramos, M., Improved method for the simnltaneons determination of whey proteins, caseins, and para-k-casein in milk and dairy prodncts by capillary electrophoresis. J. Chromatogr. A, 915, 225, 2001. 

Fig. 5 Chromatographic patterns of Teirincho cheese from the pH 4.3 insoluble fractions at 1 day of ripening. para-K-casein ots2, as2-casein a i Osi-casein Osi-I peptide P2, P2-casein Pi, Pi-casein.

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