Tritiated peptides. Part 13. Synthesis of [4,5-3H-Leu2]- and [3,4-3H-Pro6]-locust adipokinetic hormone

Abstract

The synthesis of [4,5-³H-Leu²]- and [3,4-³H-Pro⁶]-locust adipokinetic hormones by the catalytic tritiation of [4,5-dehydroLeu²]-(ΔLeu²-) and [3,4-dehydroPro⁶]-(ΔPro⁶-) precursors is described. The products had specific radioactivities of 115 and 12.1 Ci mmol^–1 respectively. The distribution of isotope in the former was investigated by ³H n.m.r. spectroscopy which confirmed the conclusions from ²H n.m.r. spectroscopy of catalytically deuteriated N-acetyl-4,5-dehydroleucine. It was concluded that the δ-methyl groups and the γ-methinyl group of leucine are the only tritiated positions in the molecule.