Fluorescence studies on the binding of a chemotactic peptide to human spermatozoa

The binding of N-Formyl-Met-Leu-Phe-Lys-Dansyl, fluorescent analog of the chemotactic peptide, Formyl-Met-Leu-Phe, to human ejaculated spermatozoa and to isolated heads and tails of spermatozoa was studied by fluorescence microscopy and spectrofluorimetry. The results indicate that the peptide binds to the surface of human spermatozoa and to isolated heads and tails of spermatozoa. The binding was not inhibited by BSA, human seminal plasma and Boc-Met-Leu-Phe-Lys but Formyl-Met-Leu-Phe-Lys reduced significantly the binding of the peptide. Evidence is also provided to indicate that the peptide binds with a higher affinity in the tail region of the spermatozoa.