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  • 1
    Electronic Resource
    Electronic Resource
    Binding of chemotactic peptide to the outer surface and to whole human spermatozoa with different affinity states (1988)
    New York, NY : Wiley-Blackwell
    Gamete Research 20 (1988), S. 233-239 
    Details
    ISSN: 0148-7280
    Keywords: human sperm ; membrane ; receptors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Binding of N-formyl-methionyl-L-leucyl-[3H]phenylalanine (fML[3H]Ph) to human ejaculated spermatozoa and to its isolated plasma membrane was studied. Our data confirm the presence of specific receptors for f-MLPh in the human spermatozoa and suggest that whole spermatozoa receptors exist in two affinity states, one high-affinity, low-capacity specific receptor (Kd = 12.3 ± 0.5 nM, n = 22,285 ± 65,008 binding sites per sperm cell) and a second one (Kd = 700 ± 47 nM) that is not saturable, indicating a low-affinity, high-capacity nonspecific site. In contrast, sperm membrane showed only one class of binding site (Kd = 6.4 ± 0.12 nM), which was statistically different from that of the high-affinity binding site of intact spermatozoa. To explain this difference we discuss the possibility that first, the two binding affinities represent two interconvertible states of a single receptor population, which, depending on the metabolic activity of spermatozoa, may change its physicochemical properties; or second, they reflect two different processes, binding and/or transport into the spermatozoa.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120200213
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  • 2
    Electronic Resource
    Electronic Resource
    Heparin and glutathione: Physiological decondensing agents of human sperm nuclei (1989)
    New York, NY : Wiley-Blackwell
    Gamete Research 23 (1989), S. 39-47 
    Details
    ISSN: 0148-7280
    Keywords: nuclei decondensation ; thiol reagents ; reduced glutathione ; glycosaminoglycan ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: It has been proposed that reduced glutathione (GSH) or other thiol reagents may partici pate in the basic mechanism by which sperm-decondensing activity is accomplished. How ever, in vitro, these reagents seem to be inactive and require the presence of other chemi cals, usually detergents. Heparin binds specifically to the sperm membrane and provokes the decondensation of human sperm and the activation of DNA transcription and synthe sis. However, the concentrations at which these effects occur seem to be higher than those expected under physiological conditions. In the present study, thiol reagents at 10 mM concentration, either alone or combined, were completely ineffective in inducing any sig nificant nuclear decondensation after prolonged exposures (24 hr) of incubation. Heparin, 153.8 μM, was capable of inducing only a small increase in nuclear swelling. However, GSH at concentrations as low as 0.1 mM in combination with heparin induces deconden sation of human sperm nuclei in vitro. When GSH concentration was kept constant at 5 mM, nuclear decondensation was induced with heparin at concentrations as low as 11.6 μM, and a maximal decondensation (90%) was obtained with only 21.6 μM of heparin. The latter is more than ten times less than the minimal active concentration of heparin used alone.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120230105
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