1qfb
From Proteopedia
THE CYCLIC PEPTIDE CONTRYPHAN-R FROM CONUS RADIATUS
Overview
Contryphan-R is a disulfide-constrained octapeptide containing a D-tryptophan that was isolated recently from venom of the cone shell Conus radiatus. The polypeptide is present in two forms in solution due to cis-trans isomerization at hydroxyproline 3. The solution structure of the major form of this unusual polypeptide, determined from NMR data, consists of a well-defined fold containing a non-hydrogen-bonded chain reversal from Gly1 to Glu5, which includes a cis-hydroxyproline and a D-Trp, and a type I beta-turn from Glu5 to Cys8. The presence of a putative salt bridge between the Glu5 carboxyl group and the N-terminal ammonium group is investigated by using various solvation models during energy minimization and is compared with the results of a pH titration. A comparison of the structure of contryphan-R with other cyclic peptide structures highlights some of the key structural determinants of these peptides and suggests that the contryphan-R fold could be exploited as a scaffold onto which unrelated protein binding surfaces could be grafted. Comparison with small disulfide-bridged loops in larger proteins shows that contryphan-R is similar to a commonly occurring loop structure found in proteins.
About this Structure
1QFB is a Single protein structure. Full crystallographic information is available from OCA.
Reference
Solution structure of contryphan-R, a naturally occurring disulfide-bridged octapeptide containing D-tryptophan: comparison with protein loops., Pallaghy PK, Melnikova AP, Jimenez EC, Olivera BM, Norton RS, Biochemistry. 1999 Aug 31;38(35):11553-9. PMID:10471307 Page seeded by OCA on Sat May 3 06:11:53 2008
