Metal clips that induce unstructured pentapeptides to be alpha-helical in water.

摘要: Short peptides corresponding to protein helices do not form thermodynamically stable helical structures in water, a solvent that strongly competes for hydrogen-bonding amides of the peptide backbone. Metalloproteins often feature metal ions coordinated amino acids within hydrogen-bonded regions structure, so there is prospect metals stabilizing or inducing short peptides. However, this has only previously been observed nonaqueous solvents under helix-favoring conditions water. Here cis-[Ru(NH(3))(4)(solvent)(2)](2+) and [Pd(en)(solvent)(2)](2+) are compared water their capacity as clips induce alpha-helicity completely unstructured five residues, Ac-HARAH-NH(2) Ac-MARAM-NH(2). More was latter pentapeptide and, when chelated ruthenium, it showed greatest yet reported metallopeptide (approximately 80%). Helicity clearly induced rather than stabilized, two methionines were 10(13)-fold more effective histidines lower oxidation state Ru(II) over Ru(III). The study identifies key factors influence stability an alpha-helical turn suggests tools folding, raises intriguing possibility transiently playing important roles native folding polypeptides