PURIFICATION AND PROPERTIES OF A HYPOGLYCAEMIC PEPTIDE FROM OX GROWTH HORMONE

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Abstract
SUMMARY: A peptide has been isolated from crystalline ox growth hormone (GH) which stimulates glucose uptake by isolated rat diaphragm when incubated with it at low concentrations (0·01 μg./ml. medium). The peptide also causes a slight but persistent hypoglycaemia in fasted mice and rabbits. The increase in glucose uptake by diaphragm is not accompanied by increased glycogen synthesis; in certain circumstances it causes a diminution in lactate output. When incubated with normal rat diaphragm in the absence of acetate, very high concentrations (10 μg./ml.) cause an inhibition of glucose uptake. The peptide appears to have negligible effects on fat metabolism. The peptide has a mol. wt. of 5,000–10,000, an isoelectric point of about pH 6, and an N-terminal methionine. The amino acid composition is noteworthy for the complete absence of basic amino acids. It is concluded that ox GH freed from this peptide will stimulate glycogen synthesis by muscle without increasing the uptake of glucose.