Preparation and some properties of the haemoglobin-binding protein of bovine blood.

Bovine haptoglobin was prepared from sera which showed peroxidase activity in the complex with haemoglobin. The procedure consisted of precipitation with ammonium sulphate at 0.5 saturation, affinity chromatography on Sepharose 4B coupled to bovine apoglobin, and gel filtration on Sepharose 4B. The preparation was heterogeneous, migrating in 7.5% polyacrylamide gel electrophoresis at pH 8.3 as four haemoglobin-binding bands. On immunoelectrophoresis with bovine antiserum the preparation formed a single precipitin arc with the mobility of alpha 2-globulin; the preparation was found to be a glycoprotein, the sugar moiety of which amounted to 16%.