Procedure for the isolation of a large peptic fragment of human serum albumin.

For a thorough investigation of the drug-binding behaviour and other physicochemical properties of human serum albumin, one needs large amounts of specific fragments of albumin. Such fragments were obtained by careful proteolysis of the native protein with pepsin at pH 3.70. The fast protein liquid chromatographic technique was used to find the optimum experimental conditions for the separation of the fragments. By means of anion-exchange chromatography, chromatofocusing and gel permeation, it was possible to obtain a large fragment with a relative molecular mass of 46,000. The fragment could be assigned to segment 1-387 and therefore consists of domains 1 and 2 of the albumin structure. A 1-g amount of albumin produced 50 mg of a fragment that was 98% homogeneous.