Isolation of highly purified sex hormone binding globulin (SHBG): evidence for microheterogeneity.

Highly purified sex hormone binding globulin (SHBG) was isolated in milligram amounts from a human serum fraction (Cohn IV-4). The final preparation was homogeneous by the criteria of polyacrylamide-gel electrophoresis. Immunological evidence for purity could be given by double diffusion according to Ouchterlony. However, following gel isoelectric focusing highly purified SHBG displayed four different bands, as could be demonstrated by staining as well as by a photoscan of the [3H]5alpha-dihydrotestosterone-SHBG complex. After incubation with neuraminidase the microheterogeneity of SHBG disappeared and the asialo-SHBG showed only one band.