Proton nuclear magnetic resonance studies of N ɛ-Me-His 2-thyroliberin. An hyperactive analogue of thyroliberin (thyrotropin-releasing factor)

Abstract

The 270 MHz Proton magnetic resonance spectra of N ɛ -Me-His 2-thyroliberin in solution in deuterium oxide and deuterated dimethylsulfoxide have been analyzed. All the spectral features (chemical shifts, coupling constants, temperature dependence of NH peptide resonances) clearly show that no significant conformational difference exists between thyroliberin and its analogue. Upon changing solvent from Me 2SO- 2H 6 to 2H 2O, both molecules undergo a conformational change which affects the car☐amide group and the backbone of the second residue.