Low-Temperature Polymorphic Phase Transition in a Crystalline Tripeptide L-Ala-L-Pro-Gly·H2O Revealed by Adiabatic Calorimetry
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Author(s)
Markin, Alexey V.
Markhasin, Evgeny
Sologubov, Semen S.
Ni, Qing Zhe
Smirnova, Natalia N.
Griffin, Robert Guy
Date Issued
February 2015
Journal
Journal of Physical Chemistry B
Publisher
American Chemical Society (ACS)
Citation
Markin, Alexey V.; Markhasin, Evgeny; Sologubov, Semen S.; Ni, Qing Zhe; Smirnova, Natalia N. and Griffin, Robert G. "Low-Temperature Polymorphic Phase Transition in a Crystalline Tripeptide." Journal of Physical Chemistry B 119, 5 (February 2015): 1787–1792 © 2015 American Chemical Society
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Author's final manuscript
Abstract
We demonstrate application of precise adiabatic vacuum calorimetry to observation of phase transition in the tripeptide l-alanyl-l-prolyl-glycine monohydrate (APG) from 6 to 320 K and report the standard thermodynamic properties of the tripeptide in the entire range. Thus, the heat capacity of APG was measured by adiabatic vacuum calorimetry in the above temperature range. The tripeptide exhibits a reversible first-order solid-to-solid phase transition characterized by strong thermal hysteresis. We report the standard thermodynamic characteristics of this transition and show that differential scanning calorimetry can reliably characterize the observed phase transition with <5 mg of the sample. Additionally, the standard entropy of formation from the elemental substances and the standard entropy of hypothetical reaction of synthesis from the amino acids at 298.15 K were calculated for the studied tripeptide.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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DOI of Published Version
https://doi.org/10.1021/jp508710g
