β-Alanyl-β-alanine in cyclic β-turned peptides

✍ Scribed by B. Di Blasio; A. Lombardi; X. Yang; C. Pedone; V. Pavone

• Publisher: Wiley (John Wiley & Sons)
• Year: 1991
• Tongue: English
• Weight: 686 KB
• Volume: 31
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360311006

✦ Synopsis

Abstract

In the present paper we describe the synthesis, purification, and single crystal x‐ray analysis of the cyclic pentapeptide cyclo‐(L‐Pro‐L‐Pro‐L‐Phe‐β‐Ala‐β‐Ala). The peptide was synthesized by classical solution methods and the cyclization of the free pentapeptide was accomplished in good yields in diluted methylenechloride solution using N,N‐dicyclohexylcarbodiimide. The compound crystallizes in the monoclinic space group P2~1~ from hot water with five solvent molecules. The Pro^1^‐Pro^2^ peptide bond is cis and the molecular conformation is stabilized by an intramolecular hydrogen bond between the CO group of the β‐Ala^5^ and the NH of the Phe^3^ residue. The Pro^1^‐Pro^2^ segment occupies the relative positions 2 and 3 of a type VIa β‐turn, while the L‐phenylalanyl‐β‐alanyl‐β‐alanine segment is incorporated in a C~13~‐like ring structure. The crystal packing is characterized by a network of 11 intermolecular hydrogen bonds involving all the remaining CO, NH, and the water molecules.