Thermal Hysteresis in the Backbone and Side-Chain Dynamics of the Elastin Mimetic Peptide [VPGVG]3 Revealed by 2H NMR
2012
Ma, Xiang | Sun, Cheng | Huang, Jiaxin | Boutis, Gregory S.
We report on experimental measurements of the backbone and side-chain dynamics of the elastin mimetic peptide [VPGVG]₃ by ²H NMR echo spectroscopy and 2D T₁–T₂ correlation relaxometry. The T₁ and T₂ relaxation times of the Gly α-deuterons and Val α-, β-, and γ-deuterons of a hydrated sample reveal a thermal hysteresis when the temperature is raised from −10 to 45 °C and then subsequently cooled back to −10 °C. In addition, near 30 °C we observe a reduction in the slope of the T₁(T) and T₂(T) heating curves, indicating a structural change that appears to be correlated well to the known inverse temperature transition of this peptide. The thermal dependence of the correlation times of the Gly α-deuterons are well fit by an Arrhenius Law, from which we measured Eₐcₜ = (20.0 ± 3.1) kJ/mol when the sample is heated and Eₐcₜ = (10.9 ± 2.8) kJ/mol when cooled. Molecular dynamics simulations support the notion that the measured activation energy is determined largely by the extent of localized water, which is observed to decrease with increasing temperature from approximately 25 to 42 °C.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library