ABSTRACT
Several naturally occurring peptides in bovine milk were characterized by tandem mass spectrometry and Edman degradation. Chromatograms of peptide fractions (passed through an ultra-filtration membrane, nominal molecular weight limit 3000) prepared from colostrum (collected immediately after parturition) and transitional milk (collected 5 days postpartum) showed that they were almost identical. In total, six peptides, α(s1)-CN (f16-23) (RPKHPIKH), α(s1)-CN (f16-24) (RPKHPIKHQ), α(s1)-CN (f17-25) (PKHPIKHQG), α(s1)-CN (f46-52) (VFGKEKV), α(s1)-CN (f94-105) (HIQKEDVPSER), and ß-CN (f121-128) (HKEMPFPK), were identified. One of the major peptides, the N-terminal fragment of αs1 -casein, varied structurally during early lactation: α(s1)-CN (f17-25) (PKHPIKHQG) and α(s1)-CN (f16-23) (RPKHPIKH)/α(s1)-CN (f16-24) (RPKHPIKHQ) were found in colostrum and transitional milk, respectively. A chemically synthesized peptide, α(s1)-CN (f16-23) (RPKHPIKH), inhibited apoptosis of bovine granulosa cells induced by serum-free conditions in a dose-dependent manner, in consequence of caspase-3 and caspase-9 suppressions. The physiological function of the peptide remains unclear, but it may have potential use as pharmaceutical agent and as an anti-apoptotic agent in cell culture medium.
Subject(s)
Caseins/chemistry , Granulosa Cells/cytology , Granulosa Cells/drug effects , Milk/chemistry , Peptides/chemistry , Peptides/pharmacology , Animals , Apoptosis/drug effects , Cattle , FemaleABSTRACT
Bactrian camel milk and colostrum are commonly used as foods in Mongolia, whose people believe that these products promote human health. It has been hypothesized that milk oligosaccharides are biologically significant components of human milk, acting as receptor analogs that inhibit the attachment of pathogenic microorganisms to the colonic mucosa, and as prebiotics, which stimulate the growth of bifidobacteria within the infant colon. To evaluate their biological significance, we studied the oligosaccharides present in samples of Bactrian camel milk and colostrum. Using (1)H-nuclear magnetic resonance spectroscopy, we identified and characterized the following oligosaccharides of camel colostrum: Gal(ß1-4)[Fuc(α1-3)]Glc (3-fucosyllactose), Gal(ß1-3)Gal(ß1-4)Glc (3'-galactosyllactose), Gal(ß1-6)Gal(ß1-4)Glc (6'-galactosyllactose), Neu5Ac(α2-3)Gal(ß1-4)Glc (3'-sialyllactose), Neu5Ac(α2-6)Gal(ß1-4)Glc (6'-sialyllactose), Neu5Ac(α2-3)Gal(ß1-3)Gal(ß1-4)Glc (sialyl-3'-galactosyllactose), Neu5Ac(α2-6)Gal(ß1-4)GlcNAc(ß1-3)Gal(ß1-4)Glc (sialyllacto-N-tetraose c), Neu5Ac(α2-3)Gal(ß1-3)[Gal(ß1-4)GlcNAc(ß1-6)]Gal(ß1-4)Glc (sialyllacto-N-novopentaose a), Gal(ß1-3)[Neu5Ac(α2-6)Gal(ß1-4)GlcNAc(ß1-6)]Gal(ß1-4)Glc (sialyllacto-N-novopentaose b); and Neu5Ac(α2-6)Gal(ß1-4)GlcNAc(ß1-3)[Gal(ß1-4)GlcNAc(ß1-6)]Gal(ß1-4)Glc (monosialyllacto-N-neohexaose). The oligosaccharides in the mature camel milk were characterized as 3'-galactosyllactose, Gal(ß1-3)[Gal(ß1-4)GlcNAc(ß1-6)]Gal(ß1-4)Glc (lacto-N-novopentaose I), and 3'-sialyllactose.
