title: Cupryphans, metal-binding, redox-active, redesigned conopeptides.
abstract: Contryphans are bioactive peptides, isolated from the venom of marine snails of the genus Conus, which are characterized by the short length of the polypeptide chain and the high degree of unusual post-translational modifications. The cyclization of the polypeptide chain through a single disulphide bond, the presence of two conserved Pro residues, and the epimerization of a Trp/Leu residue confer to Contryphans a stable and well-defined structure in solution, conserved in all members of the family, and tolerant to multiple substitutions. The potential of Contryphans as scaffolds for the design of redox-active (macro)molecules was tested by engineering a copper-binding site on two different variants of the natural peptide Contryphan-Vn. The binding site was designed by computational modeling, and the redesigned peptides were synthesized and characterized by optical, fluorescence, electron spin resonance, and nuclear magnetic resonance spectroscopy. The novel peptides, named Cupryphan and Arg-Cupryphan, bind Cu(2+) ions with a 1:1 stoichiometry and a K(d) in the 100 nM range. Other divalent metals (e.g., Zn(2+) and Mg(2+)) are bound with much lower affinity. In addition, Cupryphans catalyze the dismutation of superoxide anions with an activity comparable to other nonpeptidic superoxide dismutase mimics. We conclude that the Contryphan motif represents a natural robust scaffold which can be engineered to perform different functions, providing additional means for the design of catalytically active mini metalloproteins.
authors.affiliation: Department of Biology, University Roma Tre, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Barba
authors.forename: Anatoli P
authors.initials: AP
authors.lastname: Sobolev
authors.forename: Cristina
authors.initials: C
authors.lastname: Romeo
authors.forename: M Eugenia
authors.initials: ME
authors.lastname: Schininà
authors.forename: Donatella
authors.initials: D
authors.lastname: Pietraforte
authors.forename: Luisa
authors.initials: L
authors.lastname: Mannina
authors.forename: Giovanni
authors.initials: G
authors.lastname: Musci
authors.forename: Fabio
authors.initials: F
authors.lastname: Polticelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002413:Cations, Divalent / Q000378:metabolism*; D019295:Computational Biology; D052078:Conus Snail / Q000235:genetics*; D003300:Copper / Q000378:metabolism*; D008667:Metalloproteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010455:Peptides / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002413:Cations, Divalent; D008667:Metalloproteins; D010455:Peptides; D003300:Copper; D013482:Superoxide Dismutase