1qfb
From Proteopedia
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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 of sequence from [1] with NH2 as ligand. 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 Wed Nov 21 00:37:58 2007
