2f2j
Solution structure of [W19K, P20N, V21K]-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 PubMedThe cyclotide family of plant proteins is of interest because of their unique topology, which combines a head-to-tail cyclic backbone with an embedded cystine knot, and because their remarkable chemical and biological properties make them ideal candidates as grafting templates for biologically active peptide epitopes. The present study describes the first steps towards exploiting the cyclotide framework by synthesizing and structurally characterizing two grafted analogues of the cyclotide kalata B1. The modified peptides have polar or charged residues substituted for residues that form part of a surface-exposed hydrophobic patch that plays a significant role in the folding and biological activity of kalata B1. Both analogues retain the native cyclotide fold, but lack the undesired haemolytic activity of their parent molecule, kalata B1. This finding confirms the tolerance of the cyclotide framework to residue substitutions and opens up possibilities for the substitution of biologically active peptide epitopes into the framework. Structural plasticity of the cyclic-cystine-knot framework: implications for biological activity and drug design.,Clark RJ, Daly NL, Craik DJ Biochem J. 2006 Feb 15;394(Pt 1):85-93. PMID:16300479[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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