Crabrolin, a natural antibiotic peptide: structural properties

A joint application of experimental and computational approaches has revealed the exceptionally high attitude of crabrolin, a 13- residue peptide with sequence FLPLILRKIVTAL-NH2, to adopt alpha-helix conformation not only inmembrane-mimicking solvents but also in the presence of a not negligible amount of water. Our study shows that this propensity essentially resides in the intrinsic thermodynamic stability of alpha-helix conformation whose kinetic stability is drastically reduced in water solvent. Our analysis suggests that this is due to two effects enhanced by water: a more local effect consisting of the demolition of intrapeptide H-bonds, essential for the alpha-helix formation, and a bulk – electrostatic – effect favoring conformational states more polar than alpha-helix. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.