High resolution nuclear magnetic resonance studies of the conformation of luteinizing hormone releasing hormone (LH-RH) and its component peptides

Abstract

The ¹H and ¹³C n.m.r. spectra of luteinizing hormone releasing hormone (LH-RH) decapeptide, < Glu-His-OMe, <Glu-His-Trp-Ser-Tyr-Gly, Trp-Ser-Tyr-Gly, and Leu-Arg-Pro-GlyNH₂ have been studied. In aqueous solution the observed J_NC coupling constants are consistent with the molecules being in random coil configurations. There was no evidence for strong intramolecular hydrogen bonding involving CO ⋯ HN The similarities in ¹H and ¹³C chemical shifts between model peptides, the component peptides, and the LH-RH decapeptide suggest no specific side-chain interactions. In particular there is no stacking of the aromatic rings. The ¹³C chemical shifts of the β- and γ-¹³C carbons in Pro in LH-RH indicate Pro to be in a trans-configuration.