Structural biochemistry XIII: Synthesis of luteinizing hormone‐releasing hormone modification [Trp⁸]‐LH‐RH

A fragment condensation method was utilized for synthesis of the Trp⁸‐substituted luteinizing hormone‐releasing hormone (LH‐RH). Lert‐Butoxycarbonyl protection was employed for the α‐amino positions, and benzyl protection was used for the phenol group of Tyr and the imidazole nitrogen of His. Peptide bond‐forming reactions were performed using N‐hydroxysuccinimide (for Trp), dicyclohexylcarbodiimide‐1‐hydroxybenzotriazole, l‐ethyl‐3‐(3′‐dimethylaminopropyl)‐carbodiimide hydrochloride, or mixed carbonic anhydride methods. Biological evaluation of [Trp⁸]‐LH‐RH indicated no luteinizing hormone‐releasing activity or inhibition of luteinizing hormone release over the dose ranges studied.