Hydrogen bonding of beta-turn structure is stabilized in D(2)O

Area of Science:

• Biochemistry
• Polymer Science
• Physical Chemistry

Background:

• Elastin-like polypeptides (ELPs) exhibit a lower critical solution temperature (LCST) phenomenon, crucial for their stimuli-responsive behavior.
• Understanding factors influencing ELP phase transitions is vital for designing advanced biomaterials and drug delivery systems.

Purpose of the Study:

• To investigate the impact of ELP chain length and guest residue chemistry on LCST in both D2O and H2O.
• To correlate differences in LCST values between heavy and light water with the secondary structure formation of ELP chains.

Main Methods:

• Lower critical solution temperature (LCST) measurements in D2O and H2O.
• Circular dichroism (CD) and infrared (IR) spectroscopy for secondary structure analysis.
• Differential scanning calorimetry (DSC) for thermodynamic profiling.

Main Results:

• Significant differences in LCST were observed between D2O and H2O, correlating with secondary structure.
• Polypeptides forming greater beta-turn/beta-aggregate structures showed larger LCST shifts between H2O and D2O.
• These specific ELPs were found to be the least hydrophobic, indicating a reduced role of hydrophobicity.

Conclusions:

• Hydrogen bonding plays a more critical role than hydrophobicity in stabilizing the collapsed state of ELPs in D2O compared to H2O.
• Secondary structure formation, particularly beta-turns and aggregates, is a key determinant of the differential response of ELPs to heavy and light water.