Characterization of bovine kappa-casein fractions and the kinetics of chymosin-induced macropeptide release from carbohydrate-free and carbohydrate-containing fractions determined by high-performance gel-permeation chromatography.

Bovine kappa-casein was fractionated at pH 8.0 on DEAE-Sepharose with an NaCl gradient, followed by DEAE-cellulose chromatography using a decreasing pH gradient from pH 6.0 to 4.

Peptide substrates for chymosin (rennin): conformational studies of kappa-casein and some kappa-casein-related oligopeptides by circular dichroism and secondary structure prediction.

Circular dichroism spectra of a series of synthetic, kappa-casein-related oligopeptide substrates for chymosin in water and in surfactant solution were determined. The results show that there is a good correlation between the beta-structure forming potential of these peptides as found by using structure-predictive methods and the conformation in dilute sodium dodecyl sulfate solutions. The results support earlier suggestions concerning enzyme-substrate interaction which were made on the basis of X-ray analysis of acid proteinases.

Some association properties of bovine SH-kappa-casein.

(1) It is shown that kappa-casein association is characterized by a critical micelle concentration which decreases as the ionic strength is increased. (2) The kappa-casein polymer molecular weight was calculated from the weight-average apparent molecular weight by taking into consideration the monomer concentration and the excluded volume. The degree of polymerization is 30 and does not depend on ionic strength between 0.

The association of bovine SH-kappa-casein at pH 7.0.

The self-association of SH-kappa-casein at pH 7.0 in 0.01 M-EDTA, 0.

Purification and some physicochemical properties of bovine kappa-casein.

1. A description is given of the fractionation of kappa-casein on DEAE-cellulose using a pH gradient. With this method an improved separation of the kappa-casein components with a higher negative charge is obtained.