A hyperglycemic peptide from pituitary growth hormone: preparation with pepsin and assay in ob-ob mice

A fragment that induces glucose intolerance in hereditarily obese mice has been prepared from pituitary growth hormone(sheep and human) by controlled digestion with pepsin in 0.05 M sodium acetate buffer, pH 3.7. The digest was purified by column chromatography on Bio-Gel P-6, followed by chromatography on Bio-Rex 70 and Bio-Gel P-2; in each successive step peptide was quantitated with the fluorescamine procedure. The fragment from sheep growth hormone has these characteristics: (1) It induces glucose intolerance in fasted ob/ob female mice when injected subcutaneously in a divided dose 15 min before, and concurrently with, glucose. (2) It is a basie peptide, as judged from its elution behavior on Bio-Rex 70, H(+) form. (3) It does not crossreact with antiserum to human growth hormone in radioimmunoassay. Further purification and initial sequence determinations have been undertaken.