title: Low temperature-induced dimerization of the bovine sperm serine protease, BSp66.
abstract: BSp120 and BSp66 are trypsin-like serine proteases from bovine spermatozoa. The former is active in cryopreserved sperm samples while the latter shows proteolytic activity in recently obtained fresh sperm. Both proteases are immunologically related and co-localize in the apical portion of the sperm head. In Western blots with specific antibodies, sperm samples incubated with reducing agents showed a decrease in the amount of BSp120, while BSp66 was detected with both anti-BSp120 and anti-BSp66 antibodies. BSp120 was evident in frozen intact spermatozoa after 60 days of semen cryopreservation and the kinetic of appearance of this protein was coincident with the decrease in the amount of BSp66. Identical results were obtained by freezing sperm extracts from fresh semen at -20 degrees C. Our results suggest that BSp120 results from disulfide bond-dimerization of BSp66 and that this process may be induced by temperatures below zero in both intact spermatozoa and in sperm extracts.
authors.affiliation: Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata. CC:1245 (7600) Mar del Plata, Argentina. acesari@mdp.edu.ar
authors.forename: Andreina
authors.initials: A
authors.lastname: Cesari
authors.forename: Claudio Santiago
authors.initials: CS
authors.lastname: Cacciato
authors.forename: Rosana Esther
authors.initials: RE
authors.lastname: De Castro
authors.forename: Jorge Julián
authors.initials: JJ
authors.lastname: Sánchez
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D015925:Cryopreservation; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D005615:Freezing; D008297:Male; D019163:Reducing Agents; D012697:Serine Endopeptidases / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D013094:Spermatozoa / Q000201:enzymology*; D013997:Time Factors
chemical_list: D019163:Reducing Agents; C114880:trypsin-like serine protease; D012697:Serine Endopeptidases