title: Identification of low-abundance proteins of bovine colostral and mature milk using two-dimensional electrophoresis followed by microsequencing and mass spectrometry.
abstract: We identified several low-abundance proteins of bovine colostrum and mature milk using the immunoabsorption technique and two-dimensional electrophoresis (2-DE) followed by microsequencing and mass spectrometry. Two major milk proteins, beta-casein and immunoglobulin G (IgG), were effectively removed from the milk using immunoabsorbents. Milk samples before and after immunoabsorption were separated by 2-DE. Protein identification of the spots on 2-DE was performed by either gel comparison, microsequencing, matrix-assisted laser desorption/ionization-time of flight mass-spectrometry (MALDI-TOF-MS), peptide mass fingerprinting or peptide sequencing using tandem MS by hybrid quadrupole/orthogonal acceleration time of flight-MS (Q-TOF). Significant differences in protein patterns were observed between the low-abundance proteins of colostrum and mature milk. In addition, several low-abundance proteins including fibrinogen beta-chain, chitinase 3-like 1, alpha-antitrypsin, complement C3 alpha-chain, gelsolin and apolipoprotein H were observed only in colostrum. However, the level of beta-casein fragments increased significantly during this lactation period. alpha-Lactalbumin and beta-lactoglobulin as well as some low-abundance proteins including bovine serum albumin, serotransferrin and lactoferrin were identified in both colostral and mature milk. Low-abundance proteins in bovine colostrum may have special physiologic relevance to the health and development of calves early in lactation.
authors: JCR Pharmaceuticals Co., Ltd., Kobe, Hyogo, Japan.
authors: Masamichi
authors: M
authors: Yamada
authors: Kouki
authors: K
authors: Murakami
authors: John C
authors: JC
authors: Wallingford
authors: Yoshikazu
authors: Y
authors: Yuki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003126:Colostrum / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods*; D008894:Milk Proteins / Q000032:analysis* / Q000737:chemistry; D008969:Molecular Sequence Data; D020539:Sequence Analysis, Protein; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D008894:Milk Proteins