Human pituitary growth hormone. 44. Effects of plasmin-modified hormone and its fragments on ornithine decarboxylase activity and lipolysis

Abstract

The rat hepatic ornithine decarboxylase stimulating activity of plasmin-modified human growth hormone and its two peptide fragments has been investigated. The activity was completely retained after plasmin treatment. The NH₂-terminal fragment [Cys (Cam)⁵³-HGH-(1-134)] retained 10% of the activity, whereas the COOH-terminal fragment [Cys (Cam)^{165, 182, 189}-(141-191)] was not active. The lipolytic activity of human growth hormone was greatly reduced after plasmin treatment, as examined in isolated rabbit adipocytes. It is suggested that the structural requirements for the lipolytic activity of the hormone are different from those required for stimulation of ornithine decarboxylase activity.