RESUMO
The decapacitating fraction of human seminal plasma, which strongly interacts with concanavalin A, is constituted by high mannose-type N-linked glycoproteins, most of them of less than 44 kDa. Each component with apparent molecular mass of 30, 18, and 17 kDa respectively, as judged by SDS-PAGE, was submitted to "in gel" digestion with trypsin followed by HPLC separation of the peptides and sequencing. They were characterized at microscale as gp17, an aspartyl protease that possibly contributes to liquefaction of the seminal plasma coagulum, two fragments of human acid phosphatase (17 and 30 kDa, respectively), and a 17-kDa fragment of carboxypeptidase E. Neither the fragments of prostatic acid phosphatase nor that of carboxypeptidase E had been described before in the human seminal fluid. Very weak bands, of apparent molecular masses 44 and 52 kDa, are consistent with presence of small amounts of parent compounds, prostatic acid phosphatase and carboxypeptidase E.
Assuntos
Carboxipeptidase H/isolamento & purificação , Concanavalina A/metabolismo , Glicoproteínas/isolamento & purificação , Fragmentos de Peptídeos/isolamento & purificação , Proteínas Tirosina Fosfatases/isolamento & purificação , Sêmen/química , Fosfatase Ácida , Sequência de Aminoácidos , Carboxipeptidase H/metabolismo , Cromatografia de Afinidade , Cromatografia Líquida de Alta Pressão , Glicoproteínas/química , Glicoproteínas/metabolismo , Humanos , Dados de Sequência Molecular , Peso Molecular , Fragmentos de Peptídeos/metabolismo , Proteínas Tirosina Fosfatases/química , Proteínas Tirosina Fosfatases/metabolismo , Sêmen/enzimologiaRESUMO
These studies showed that the fractionation of bovine seminal plasma based on lectin agarose affinity chromatography, employing lectins specific to asparagine linked oligosaccharides, and a lectin specific for fucosylated glycans, lead to products with an inhibitory effect on the acrosine-like protease activity. This effect decreases when glycocompounds containing fucosylated Lewis(x) structures are removed, suggesting that these compounds might have some role in the modulation of this activity in the bull. In the fraction devoid of high mannose, hybrid and non-bisecting lactosaminic oligosaccharide-containing glycocompounds, PDC-109 and aSFP proteins were detected and characterized at microscale.
Assuntos
Cromatografia de Afinidade/métodos , Endopeptidases/metabolismo , Inibidores de Proteases/farmacologia , Proteínas/análise , Proteínas/química , Sêmen/química , Sequência de Aminoácidos , Animais , Bovinos , Cromatografia em Gel , Eletroforese em Gel de Poliacrilamida , Endopeptidases/química , Lectinas/química , Masculino , Inibidores de Proteases/química , Proteínas de Plasma SeminalRESUMO
Fucosylated glycoconjugates play an important role in fertilization as the recognition signal of the zona pellucida. In this work, using "critical" concentrations of either, FITC Lotus tetragonolobus lectin or FITC alpha-L-fucosyl-BSA neoglycoprotein as molecular probes, population densities of fucosylated glycoconjugates and of their "complementary" molecules (carrying fucosyl receptors), were found all over the sperm surface with higher population densities in post acrosomal sheath, neck and midpiece. These results were compared with previously reported data on the population densities of lactosaminic compounds and their "complementary" molecules, obtained on same samples of spermatozoa. Statistical data demonstrate that fucosylated glycoconjugates share the same domains with biantennary N-acetyllactosaminic oligosaccharides carrying outer galactose and bisected N-acetylglucosamine residues. These domains highly differ with those of the lactosaminic glycoproteins carrying tri and tetraantennary N-acetyllactosaminic oligosaccharides. These studies also show that the domains of fucosylated glycoconjugates and their "complementary" molecules (carrying fucosyl receptors) locate in different zones of the spermatozoon than those of the compounds carrying beta-galactosyl receptors. Besides, the results suggest structural differences between fucosylated glycoconjugates of the acrosome, equatorial zone and post acrosomal sheath. This may be relevant to the different biological behavior of these compounds and zones, in fertilization.
Assuntos
Amino Açúcares/química , Fucose/química , Galactose/química , Glicoconjugados/química , Espermatozoides/química , Amino Açúcares/metabolismo , Sítios de Ligação/fisiologia , Fluoresceína-5-Isotiocianato , Hormônio Foliculoestimulante/química , Hormônio Foliculoestimulante/metabolismo , Fucose/metabolismo , Galactose/metabolismo , Glicoconjugados/metabolismo , Humanos , Lectinas , Hormônio Luteinizante/química , Hormônio Luteinizante/metabolismo , Masculino , Estrutura Terciária de Proteína , Espermatozoides/ultraestruturaRESUMO
The horseradish peroxidase (HRP), a glycoprotein rich in mannose and N-acetylglucosamine residues has been used as a ligand to detect receptors for N-glycosidic linked oligosaccharides of glycoproteins in the human spermatozoon. Specific binding of HRP occurred to the membrane and the binding sites were visualized with 3,3'-diaminobenzidine-H2O2 (DAB-H2O2) reagent, and by fluorescence when the FITC-peroxidase was used. This specific binding was suppressed by alpha-D-methyl-mannoside and human chorionic gonadotropin, decreased by follicle stimulating and luteinizing hormones and slightly diminished by N-acetylglucosamine. The distribution of the N-linked oligosaccharide specific receptors for glycoproteins in the different zones of the membrane of the spermatozoon was determined by counting the spermatozoa labeled in those zones. The pattern of the distribution is similar to that found for N-linked oligosaccharides containing glycoproteins of the same membrane. The similarity of these distributions together with the general model for cell-to-cell recognition suggest that the sperm-egg interaction mechanism could consist of dual interactions by double binding receptors.