Protein differences between normal and oligospermic human sperm demonstrated by two-dimensional gel electrophoresis

Protein expression by sperm obtained from men with normal semen analysis and men with oligospermia were evaluated by two-dimensional gel electrophoresis. Proteins were solubilized in a 9.5 M urea/2% Nonidet-P40 (LKB, Bromma, Sweden) lysis buffer and underwent second dimension separation on 10 to 16% polyacrylamide gradient gels. A set of 36 invariant proteins was identified in all normospermic samples, whereas 8 of 10 evaluable oligospermic samples lacked 1 or more of the invariant proteins. Proteins absent in oligospermic samples may be critical to normal sperm function and may serve as markers for infertility.