Insulin-potentiating action of human growth hormone. Synthesis and activity of N-terminal fragments.

Four peptides from the N-terminal region of human growth hormone have been synthesized by the solid-phase method: hGH(6-13), hGH(7-13), hGH(8-13) and hGH(9-13). Although these peptides contain the sensitive -Asp-Asn-sequence, apparently homogeneous products were obtained by synthesis on polystyrene resin, cleavage by hydrogen fluoride and purification by ion-exchange chromatography. The insulin-potentiating activity of these peptides is reported. The data indicates that extension of hGH(9-13) at its N-terminus is required for in vitro activity.