ABSTRACT
Peptides homologous to Cys53 44-77 and Cys53 52-77 of the human growth hormone molecule were prepared by solid-phase synthesis and tested by our acute glucose tolerance test in ob/ob mice. Peptide 44-77, as either the Acm-Cys53 or Cam-Cys53 derivative, adversely affects glucose tolerance at doses of 100 to 150 nmol. Peptide 52-77 is nonhyperglycemic. Other diabetogenic properties are being tested.
Subject(s)
Growth Hormone , Peptide Fragments , Amino Acids/analysis , Animals , Biological Assay , Blood Glucose/metabolism , Humans , Hyperglycemia/chemically induced , Mice , Mice, ObeseSubject(s)
Insulin/pharmacology , Adipose Tissue/drug effects , Animals , Cyclic AMP/physiology , Dogs , Glucose/metabolism , Hexokinase/metabolism , History, 20th Century , In Vitro Techniques , Insulin/history , Liver/drug effects , Muscles/drug effects , Pituitary-Adrenal System/drug effects , Rats , Receptor, Insulin/physiologyABSTRACT
Studies in female ob/ob mice demonstrated diabetogenic properties of human growth hormone (somatotropin) and of a fragment generated therefrom by controlled digestion with pepsin; both the fragment and parent growth hormone produce long-term effects on carbohydrate metabolism; in acute glucose tolerance tests, only the fragment is active. Two nonacidic diabetogenic fractions have been separated from inactive fractions by chromatography on Bio-Gel P-6 followed by ion exchange chromatography at pH 4.3 and gel filtration on Bio-Gel P-2 and/or Sephadex G25; these active fractions exhibited multiple NH2-terminal (Lys, Phe, Leu, and Tyr). Fraction CD has these characteristics: (i) It induces glucose intolerance in fasting female ob/ob mice when injected subcutaneously in a divided dose, 15 min before and concurrently with glucose; mice injected with sufficient peptide exhibit elevated fasting glucose levels as long as 7 months after a single glucose tolerance test. (ii) It is a peptide smaller than that reported to stimulate body growth, but larger than somatostatin. This peptide, as reported earlier, does not crossreact with antiserum to human growth hormone in radioimmunoassay.
Subject(s)
Diabetes Mellitus/chemically induced , Growth Hormone , Peptides/isolation & purification , Amino Acid Sequence , Animals , Blood Glucose/metabolism , Diabetes Mellitus/blood , Female , Growth Hormone/analysis , Mice , Mice, Obese , Molecular Weight , Structure-Activity Relationship , Time FactorsABSTRACT
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.
