The presence in human spermatozoa of sites binding some proteins of the outer membrane of Escherichia coli.

: In previous works, we noted that porins, surface components of Gram negative bacteria, are toxic for human spermatozoa. In this work we see that porins of E. coli labeled with I125 (0.1-1.0 microgram/ml) bind to spermatozoa, showing the presence of saturable molecular configurations of 0.5-0.6 micrograms/ml. In the presence of non labeled porins, the binding of labeled porins to the spermatozoa is greatly reduced. At saturating concentrations of 0.6 micrograms/ml labeled porins, the binding reaches a saturation plateau at about 15 min.