A rapid procedure for the isolation of human sex steroid binding protein

A three stage procedure is described which provides a rapid, simple, and reliable means to isolate sex steroid binding protein from human serum. Purification is achieved by the sequential use of affinity chromatography, isoelectric focusing in granulated gels and ion exchange chromatography. Between 3--4 mg of protein can be recovered from one litre of pregnancy serum without four days. A molecular radius of 2.98 nm and an apparent molecular mass of 91 000 were obtained for the purified native protein by polyacrylamide gel electrophoresis. A value of 50 000 was obtained for the molecular mass of the reduced protein by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The purified protein was used to prepare a monospecific rabbit antiserum and a murine monoclonal antibody. Partial characterisation of the latter has been achieved.