Several proteins in milk have been shown to have physiological functions. While some proteins present in whey demonstrate antibacterial activity involved in immune function, provide amino acids, and facilitate nutrient uptake for the developing young, casein in milk have shown to exhibit different functions, such as its role in mineral absorption as well as its ability to exhibit opiate-like effects and anti-adhesive properties. Although caseins in many species have been well documented, casein represents the least characterized and understood class of proteins in cat milk. In this study, mature cat milk samples (1 mo of lactation) were collected from domestic shorthair cats. A method was developed for efficient isolation of casein from whey proteins in cat milk. The casein subunits were separated by fast protein liquid chromatography (FPLC) using gel filtration and anion-exchange (Mono-Q) columns. Purity of the separated proteins was assessed by polyacrylamide gradient gel electrophoresis. Differences between phosphorylated and glycosylated casein subunits were determined using a differential staining method. Phosphorylated casein subunits with MWs ranging from 26 kD to 32 kD were isolated. A comparison of their amino acid composition to known caseins from other species suggest that they are different phosphorylated forms of β-casein. A partial amino acid sequence from the N-terminus of a 32 kD band confirmed the presence of β-casein.
|Original language||English (US)|
|State||Published - 1997|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology