TY - JOUR
T1 - Heat Capacity Changes (Δ Cp) for Interconversions between Differentially-Ordered DNA States within Physiological Temperature Domains
T2 - Implications for Biological Regulatory Switches
AU - Völker, Jens
AU - Plum, G. Eric
AU - Breslauer, Kenneth J.
N1 - Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/7/9
Y1 - 2020/7/9
N2 - Knowledge of differences in heat capacity changes (ΔCp) between biopolymer states provides essential information about the temperature dependence of the thermodynamic properties of these states, while also revealing insights into the nature of the forces that drive the formation of functional and dysfunctional biopolymer "order."In contrast to proteins, for nucleic acids there is a dearth of direct experimental determination of this information-rich parameter, a deficiency that compromises interpretations of the ever-increasing thermodynamic analyses of nucleic acid properties; particularly as they relate to differential nucleic acid (meta)stability states and their potential biological functions. Here we demonstrate that such heat capacity differences, in fact, exist not only between traditionally measured native to fully unfolded (assumed "random coil") DNA states, but also between competing order-to-order transformations. We illustrate the experimental approach by measuring the heat capacity change between "native"/ordered, sequence homologous, "isomeric"DNA states that differ in conformation but not sequence. Importantly, these heat capacity differences occur within biologically relevant temperature ranges. In short, we describe a new and general method to measure the value of such heat capacity differences anywhere in experimentally accessible conformational and temperature space; in this case, between two metastable bulge loop states, implicated in DNA expansion diseases, and their competing, fully paired, thermodynamically more stable duplex states. This measurement reveals a ΔCp of 61 ± 7 cal molbp-1 K -1. Such heat capacity differences between competing DNA "native"ensemble states must be considered when evaluating equilibria between different DNA "ordered"conformations, including the assessment of the differential stabilizing forces and potential biological functions of competing DNA "structured"motifs.
AB - Knowledge of differences in heat capacity changes (ΔCp) between biopolymer states provides essential information about the temperature dependence of the thermodynamic properties of these states, while also revealing insights into the nature of the forces that drive the formation of functional and dysfunctional biopolymer "order."In contrast to proteins, for nucleic acids there is a dearth of direct experimental determination of this information-rich parameter, a deficiency that compromises interpretations of the ever-increasing thermodynamic analyses of nucleic acid properties; particularly as they relate to differential nucleic acid (meta)stability states and their potential biological functions. Here we demonstrate that such heat capacity differences, in fact, exist not only between traditionally measured native to fully unfolded (assumed "random coil") DNA states, but also between competing order-to-order transformations. We illustrate the experimental approach by measuring the heat capacity change between "native"/ordered, sequence homologous, "isomeric"DNA states that differ in conformation but not sequence. Importantly, these heat capacity differences occur within biologically relevant temperature ranges. In short, we describe a new and general method to measure the value of such heat capacity differences anywhere in experimentally accessible conformational and temperature space; in this case, between two metastable bulge loop states, implicated in DNA expansion diseases, and their competing, fully paired, thermodynamically more stable duplex states. This measurement reveals a ΔCp of 61 ± 7 cal molbp-1 K -1. Such heat capacity differences between competing DNA "native"ensemble states must be considered when evaluating equilibria between different DNA "ordered"conformations, including the assessment of the differential stabilizing forces and potential biological functions of competing DNA "structured"motifs.
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U2 - 10.1021/acs.jpcb.0c04065
DO - 10.1021/acs.jpcb.0c04065
M3 - Article
C2 - 32531155
AN - SCOPUS:85088209497
SN - 1520-6106
VL - 124
SP - 5614
EP - 5625
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 27
ER -