Immunoelectrophoretic Studies of the β₁-Hæmbinding Globulin (Hæmopexin) in Hereditary Hæmolytic Disorders

Abstract

NEALE et al.¹ have demonstrated by paper electrophoresis a hæm-binding globulin in the β-globulin fraction of human serum. Since then, several investigators examined this protein^2–6, which was identified by immunoelectrophoresis with β₁-B-globulin and called hæmopexin⁷. On starch-gel electrophoresis the hæm-binding protein was found to migrate with the fast α₂-globulins^8,9. Hæmopexin is present in the perchloric acid-soluble fraction of serum^7,10 from which Schultze et al.¹¹ obtained a highly purified preparation by combined ammonium sulphate precipitation and zone electrophoresis. Hæmopexin is a glycoprotein containing approximately 20 per cent carbohydrate and has a sedimentation rate of 4.8S corresponding to a molecular weight of approximately 80,000. The purified protein has a binding capacity of 15–20 mols hæmin per mol hæmopexin; evidence for binding of hæmoglobin or cytochrome c could not be obtained. The hæmin binding capacity of normal human serum is approximately 10 mg/100 ml. (refs. 2 and 9).