  Responsiveness of polypeptides and polymers in aqueous solution plays an
important role in biomedical applications and in designing advanced functional
materials. Elastin-like polypeptides (ELPs) are a well-known class of synthetic
intrinsically disordered proteins (IDPs), which exhibit a lower critical
solution temperature (LCST) in pure water. The LCST transition can be further
tuned by proline isomerization. Here, we study and compare the influence of
cis/trans proline isomerization on the collapse of single ELPs in aqueous
solution. Our results reveal that cis isomers play an important role in tuning
the phase behavior of ELPs by hindering peptide-water hydrogen bonding while
promoting intramolecular interactions.
