Preliminary characterization of a new androgen-binding protein in human seminal plasma

In order to obtain comparative analysis between the steroid binding proteins from blood serum and seminal plasma, fresh samples were incubated and assayed in parallel with the following tritiated steroids: dihydrotestosterone, testosterone, cortisol, progesterone and estradiol. Thereafter, and using techniques such as (1) polyacrilamide disk gel electrophoresis with elution of proteins from the gel slices, (2) ammonium sulphate precipitation, (3) enzymatic hydrolysis, and (4) gel filtration on Sephadex G-100, there was a resemblance in the electrophoretic patterns confirming the presence in both fluids of proteins like TeBG, CBG, and Albumin, previously described in blood serum. In seminal fluid, but not in blood serum, another small protein with androgen binding capacity was found and its preliminary characterization demonstrated: disappearance with enzymatic treatment, low molecular weight, negative charge, and precipitation range with ammonium sulphate from 30 to 35%. Its elution profile on Sephadex G-100 was contaminated with albumin.