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Racemic structure of cyclic Vc1.1 (cVc1.1-1)
Structural highlights
FunctionCA1A_CONVC Alpha-conotoxins act on postsynaptic membranes, they bind to the nicotinic acetylcholine receptors (nAChR) and thus inhibit them. This synthetic peptide (produced without hydroxyproline, nor 4-carboxyglutamate) is a neuronal nAChR antagonist that acts as a powerful analgesic. It blocks nAChRs composed of alpha-3 or -5/beta-2 (IC(50)=7.2 uM), alpha-3/beta-2 (IC(50)=7.3 uM), alpha-3/beta-4 (IC(50)=4.2 uM), alpha-3 or -5/beta-4 (IC(50)<30 uM), alpha-4/beta-2 (IC(50)<30 uM), alpha-4/beta-4 (IC(50)<30 uM) and alpha/beta/gamma/delta (IC(50)<30 uM) subunits.[1] [2] Publication Abstract from PubMedCyclic disulfide-rich peptides have exceptional stability and are promising frameworks for drug design. We were interested in obtaining X-ray structures of these peptides to assist in drug design applications, but disulfide-rich peptides can be notoriously difficult to crystallize. To overcome this limitation, we chemically synthesized the L- and D-forms of three prototypic cyclic disulfide-rich peptides: SFTI-1 (14-mer with one disulfide bond), cVc1.1 (22-mer with two disulfide bonds), and kB1 (29-mer with three disulfide bonds) for racemic crystallization studies. Facile crystal formation occurred from a racemic mixture of each peptide, giving structures solved at resolutions from 1.25 A to 1.9 A. Additionally, we obtained the quasi-racemic structures of two mutants of kB1, [G6A]kB1, and [V25A]kB1, which were solved at a resolution of 1.25 A and 2.3 A, respectively. The racemic crystallography approach appears to have broad utility in the structural biology of cyclic peptides. Racemic and Quasi-Racemic X-ray Structures of Cyclic Disulfide-Rich Peptide Drug Scaffolds.,Wang CK, King GJ, Northfield SE, Ojeda PG, Craik DJ Angew Chem Int Ed Engl. 2014 Aug 28. doi: 10.1002/anie.201406563. PMID:25168664[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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