title: A naturally occurring α(s1)-casein-derived peptide in bovine milk inhibits apoptosis of granulosa cells induced by serum-free conditions.
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 β-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.
authors.affiliation: Department of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Inada-cho, Obihiro, 080-8555, Hokkaido, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: K
authors.initials: K
authors.lastname: Ganzorig
authors.forename: A
authors.initials: A
authors.lastname: Miyamoto
authors.forename: T
authors.initials: T
authors.lastname: Ishii
authors.forename: T
authors.initials: T
authors.lastname: Urashima
authors.forename: K
authors.initials: K
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002364:Caseins / Q000737:chemistry*; D002417:Cattle; D005260:Female; D006107:Granulosa Cells / Q000166:cytology* / Q000187:drug effects*; D008892:Milk / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D002364:Caseins; D010455:Peptides
keywords: Bos taurus; anti-apoptotic activity; casein; milk peptides