NMR Studies of Ni-binding Luteinizing Hormone Releasing Hormone

Abstract

Luteinizing Hormone Releasing Hormone (LHRH) is composed of 10 amino acids, and is best known as a neurotransmitter. Because of the 80% homology in animals, much more concerns have focused on the substances that have similar functions or can control LHRH. Ni,Cu-LHRH complexes were synthesized. The degree of complexation was monitored by 1H, 13C-NMR chemical shifts, and final products were identified by ESI-Mass spectrum. Solution-state structure determination of Ni-LHRH complex was accomplished by using NMR results and NMR-based distance geometry (DG). Interproton distances from nuclear Overhauser effect spectroscopy (NOESY) were utilized for the molecular structure determination. Results were compared with previous structures obtained from energy minimization and other spectroscopic methods. Structure obtained in this study has a cyclic conformation which is similar to that of energy minimized, and exhibits a specific α-helical turn with residue numbers (2～7) out of 10 amino acids. Comparison of chemical shifts and EPR studies of Ni,Cu-LHRH complexes exhibit that Ni-LHRH complex has same binding sites with the 4-coordination mode as in Zn-LHRH complex.