Secondary structure formation and LCST behavior of short elastin-like peptides.

This contribution investigates the effects of chain length and chemical composition on the secondary structure and LCST behavior of a library of short, elastin-like peptides based on the GVGVP motif. CD experiments revealed that most of the investigated peptides showed the typical elastin conformational behavior with a decrease in random coil and an increase in beta-turn character with increasing temperature. For several peptides, LCST behavior was observed in aqueous NaCl solutions containing 10 mg/mL peptide. By extrapolation of the LCSTs measured at different NaCl concentrations to zero-salt concentration, apparent LCSTs were determined. The apparent LCST was found to decrease with increasing peptide chain length, which correlated well with the trend in the predicted partition coefficients. The apparent LCST of the peptides could be manipulated by successive replacement of the valine residues by more hydrophobic isoleucine, leucine, or phenylalanine residues. Within a particular series of variants, the apparent LCST was found to decrease with an increasing number of valine replacements, which also correlated well with the predicted evolution of the partition coefficient. Although the relative importance of the overall peptide hydrophobicity and the conformational preferences of the constituent amino acids on the LCST behavior still remains an open question, the results described in this contribution clearly demonstrate that short, elastin-like peptides are potentially attractive building blocks for a range of materials applications in biomedicine and engineering.