title: Structural characterization of the oligosaccharide chains of native and crystallized boar seminal plasma spermadhesin PSP-I and PSP-II glycoforms.
abstract: The PSP-I/PSP-II heterodimer is the major protein of boar seminal plasma. Both subunits are glycoproteins of the spermadhesin family and each contains a single N-glycosylation site. After enzymatic release of the oligosaccharides from isolated PSP-I and PSP-II, mainly neutral and monosialylated oligosaccharides, and small amounts of disialylated oligosaccharides, were recovered from both proteins. Twenty-two neutral oligosaccharides, 11 monosialylated glycans and three disialylated carbohydrate chains were characterized using mass spectrometric and NMR techniques. PSP-I and PSP-II share the same glycans but differ in their relative molar ratios. Most glycan structures are proximally alpha1-6-fucosylated, diantennary complex-type bearing nonsialylated or alpha2-6-sialylated N-acetyllactosamine or di-N-acetyllactosamine antennae. The majority of nonsialylated N-acetyllactosamine antennae bear terminal alpha1-3-linked Gal residues. In addition, the N-acetylglucosamine residue of nonsialylated N-acetyl and di-N-acetyllactosamine antennae can be modified by an alpha1-3-linked fucose residue. Structures of higher antennarity, as well as structures 3,6-branched at galactose residues, were found in smaller amounts. In one oligosaccharide, N-acetylneuraminic acid is substituted by N-glycolylneuraminic acid. Mass spectrometric analysis of PSP-I and PSP-II glycoforms isolated from crystallized PSP-I/PSP-II heterodimer showed the coexistence of major PSP-I and PSP-II glycoforms in the hexagonal crystals. Oligosaccharides with the NeuNAcalpha2-6GalNAcbeta1-4GlcNAc-R motif block adhesive and activation-related events mediated by CD22, suggesting a possible immunoregulatory activity for PSP-I/PSP-II.
authors.affiliation: Gesellschaft für Biotechnologische Forschung (GBF) mbH, Braunschweig, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Nimtz
authors.forename: E
authors.initials: E
authors.lastname: Grabenhorst
authors.forename: H S
authors.initials: HS
authors.lastname: Conradt
authors.forename: L
authors.initials: L
authors.lastname: Sanz
authors.forename: J J
authors.initials: JJ
authors.lastname: Calvete
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D019281:Dimerization; D006023:Glycoproteins / Q000737:chemistry*; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008745:Methylation; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D012661:Semen / Q000737:chemistry; D029607:Seminal Vesicle Secretory Proteins; D017421:Sequence Analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013552:Swine
chemical_list: D006023:Glycoproteins; D009844:Oligosaccharides; D029607:Seminal Vesicle Secretory Proteins; C074521:seminal vesicle secretory protein II, porcine; C074520:seminal vesicle secretory protein 109, porcine