Homogeneity studies on human growth hormone

Abstract

Human growth hormone preparations (Raben) have been found to contain 10-40% of denatured growth hormone as shown by radioimmunoassay, reaction of radioiodinated subtractions with antiserum to whole growth hormone, and amino acid analysis and confirmed by bioassay using the tibia test. The altered fraction was more electronegative than the intact hormone on starch-grain electrophoresis in barbitone buffer pH 8.6. Some heterogeneity of the active material was detectable in simple buffer extracts of a single acetone-stored pituitary gland. The inert fraction was more completely separated from the active hormone as an unre-tarded fraction from Sephadex G-200 columns with a borate buffer. This separation was due to aggregation of the denatured growth hormone in borate buffer. The active traction from the Sephadex column still contained some inert material and the amount of this remaining varied considerably between different batches of growth hormone. The radioimmunoassay procedure detects only the immunologically and biologically intact fraction.