Lack of Effect of a Cyanogen Bromide Fragment of Human Growth Hormone on Some Aspects of Carbohydrate Metabolism in Vitro

Abstract

Summary

It has recently been claimed that a pituitary peptide which inhibits several phases of carbohydrate and lipid metabolism is identical with the COOH-terminal 25-amino acid portion of human growth hormone. However, the active factor has always been obtained in low yield and impure condition. We have used cyanogen bromide to prepare the COOH-terminal 21-amino acid peptide of human growth hormone. This fails to inhibit any of three systems inhibited by the reputed active fraction: glyceraldehyde 3-phosphate dehydrogenase, α-glycerophosphate dehydrogenase, and glucose uptake by rat soleus muscle. Unless the first four amino acids are essential, the identification of the inhibitory factor as the COOH-terminal 25-amino acid peptide of human growth hormone is not justified.

The author thanks Dr. David Scott of Auckland Public Hospital for the supplies of human growth hormone. He also appreciates the helpful suggestions and encouragement of Dr. J. Nielsen and Professor J. G. T. Sneyd. Mr. I. C. T. Lyon performed the amino acid analyses.