4tto
Quasi-racemic structure of [V25A] kalata B1
Structural highlights
FunctionKAB1_OLDAF Probably participates in a plant defense mechanism. Has antibiotic activity. Has a diuretic effect. Has a uterotonic effect in humans. Active against the Gram-positive S.aureus with a minimum inhibition concentration of approximately 0.2 microM. Relatively ineffective against Gram-negative bacteria such as E.coli and P.aeruginosa. Inhibitory effect on the growth and development of larvae from H.punctigera. The unmodified form has hemolytic activity, the oxidized form lacks hemolytic activity. If the protein is linearized, hemolytic activity is lost.[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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