| Abstract: | Abstract: Leuprolide acetate (pGlu‐His‐Trp‐Ser‐Tyr‐d ‐Leu‐Leu‐Arg‐Pro‐NHEt), a potent LHRH agonist in wide clinical use, was characterized conformationally by NMR and circular dichroism. It displayed quite different preferred conformations under different solution conditions: two low population β‐turns in water, a nascent helix in TFE/water at low pH, and a high population β‐turn in TFE/water at slightly acidic pH. The pH‐related conformational change in TFE/water is attributed to the pKa of the acetate counterion, not to ionizable groups on the peptide. None of these conformations are in exact agreement with previous computational predictions. |
