Human seminal plasma contains a protein factor that can inhibit the motility of both demembranated-reactivated and intact spermatozoa. This factor, named seminal plasma motility inhibitor (SPMI), was orignally isolated from seminal plasma and shown to orginate exclusively from the seminal vesicles, where its specific activity is 5- to 10-fold higher than it is in seminal plasma. The present study aimed at investigating the mechanism responsible for this difference in activity. Analysis of semen after ejaculation allowed to demonstrate that this difference in SPMI specific activity is due to the presence of a predominant 52 kDa SPMI precursor form in seminal vesicle fluid which is rapidly degraded after ejaculation by prostatic proteases. In addition, SPMI precursor was found to be associated with semen coagulum proteins and abnormal processing of the precursor in semen was associated with poor sperm motility. / A novel method was developed to purify SPMI precursor from seminal vesicle fluid and semen coagulum. Prostate-specific antigen (PSA) hydrolyzed SPMI precursor in a manner reminiscent of its processing in whole semen. Biochemical analysis of the precursor protein and its hydrolysis products provided evidence that SPMI precursor is identical to semenogelin, the main structural protein of semen coagulum. The purified precursor inhibited the motility of intact spermatozoa in a reversible and dose-dependent manner. / Finally, the characterization of SPMI molecular processing by PSA was addressed. The results directly demonstrate for the first time the restricted chymotrypsin-like specificity of PSA on its major physiological substrate. The sites of hydrolysis by PSA were identified along the precursor molecule and specific domains within the SPMI precursor responsible for biological activity and reactivity with various antibodies were mapped. / Overall, these results shed light on the photeolytic precessing of SPMI precursor occurring after ejaculation, and the associated change in SPMI activity on spermatozoa. The present findings provide evidence, for the first time, that a specific protein appears responsible for the observed low sperm motility in freshly ejaculated semen, and that its processing by PSA parallels the progressive increase in sperm motility observed during semen liquefaction.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.40237 |
| Date | January 1996 |
| Creators | Robert, Martin, 1967- |
| Contributors | Gagnon, Claude (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Surgical Research.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001495041, proquestno: NN12467, Theses scanned by UMI/ProQuest. |
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