Thermodynamics of DNA: heat capacity changes on duplex unfolding

Anatoliy Dragan; Peter Privalov; Colyn Crane-Robinson

doi:10.1007/s00249-019-01403-1

Thermodynamics of DNA: heat capacity changes on duplex unfolding

Anatoliy Dragan, Peter Privalov, Colyn Crane-Robinson

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Abstract

The heat capacity change, ΔCp, accompanying the folding/unfolding of macromolecules reflects their changing state of hydration. Thermal denaturation of the DNA duplex is characterized by an increase in ΔCp but of much lower magnitude than observed for proteins. To understand this difference, the changes in solvent accessible surface area (ΔASA) have been determined for unfolding the B-form DNA duplex into disordered single strands. These showed that the polar component represents ~ 55% of the total increase in ASA, in contrast to globular proteins of similar molecular weight for which the polar component is only about 1/3rd of the total. As the exposure of polar surface results in a decrease of ΔCp, this explains the much reduced heat capacity increase observed for DNA and emphasizes the enhanced role of polar interactions in maintaining duplex structure. Appreciation of a non-zero ΔCp for DNA has important consequences for the calculation of duplex melting temperatures (T_m). A modified approach to T_m prediction is required and comparison is made of current methods with an alternative protocol.

Original language	English
Pages (from-to)	773-779
Number of pages	7
Journal	European Biophysics Journal
Volume	48
Issue number	8
Early online date	5 Nov 2019
DOIs	https://doi.org/10.1007/s00249-019-01403-1
Publication status	Published - 1 Dec 2019

Keywords

DNA
heat capacity
hydration
solvent accessible surface area
surface polarity

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10.1007/s00249-019-01403-1

Thermodynamics of DNAFinal published version, 1.19 MBLicence: CC BY

http://link.springer.com/10.1007/s00249-019-01403-1

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title = "Thermodynamics of DNA: heat capacity changes on duplex unfolding",

abstract = "The heat capacity change, ΔCp, accompanying the folding/unfolding of macromolecules reflects their changing state of hydration. Thermal denaturation of the DNA duplex is characterized by an increase in ΔCp but of much lower magnitude than observed for proteins. To understand this difference, the changes in solvent accessible surface area (ΔASA) have been determined for unfolding the B-form DNA duplex into disordered single strands. These showed that the polar component represents ~ 55% of the total increase in ASA, in contrast to globular proteins of similar molecular weight for which the polar component is only about 1/3rd of the total. As the exposure of polar surface results in a decrease of ΔCp, this explains the much reduced heat capacity increase observed for DNA and emphasizes the enhanced role of polar interactions in maintaining duplex structure. Appreciation of a non-zero ΔCp for DNA has important consequences for the calculation of duplex melting temperatures (Tm). A modified approach to Tm prediction is required and comparison is made of current methods with an alternative protocol.",

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T1 - Thermodynamics of DNA: heat capacity changes on duplex unfolding

AU - Dragan, Anatoliy

AU - Privalov, Peter

AU - Crane-Robinson, Colyn

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Y1 - 2019/12/1

N2 - The heat capacity change, ΔCp, accompanying the folding/unfolding of macromolecules reflects their changing state of hydration. Thermal denaturation of the DNA duplex is characterized by an increase in ΔCp but of much lower magnitude than observed for proteins. To understand this difference, the changes in solvent accessible surface area (ΔASA) have been determined for unfolding the B-form DNA duplex into disordered single strands. These showed that the polar component represents ~ 55% of the total increase in ASA, in contrast to globular proteins of similar molecular weight for which the polar component is only about 1/3rd of the total. As the exposure of polar surface results in a decrease of ΔCp, this explains the much reduced heat capacity increase observed for DNA and emphasizes the enhanced role of polar interactions in maintaining duplex structure. Appreciation of a non-zero ΔCp for DNA has important consequences for the calculation of duplex melting temperatures (Tm). A modified approach to Tm prediction is required and comparison is made of current methods with an alternative protocol.

AB - The heat capacity change, ΔCp, accompanying the folding/unfolding of macromolecules reflects their changing state of hydration. Thermal denaturation of the DNA duplex is characterized by an increase in ΔCp but of much lower magnitude than observed for proteins. To understand this difference, the changes in solvent accessible surface area (ΔASA) have been determined for unfolding the B-form DNA duplex into disordered single strands. These showed that the polar component represents ~ 55% of the total increase in ASA, in contrast to globular proteins of similar molecular weight for which the polar component is only about 1/3rd of the total. As the exposure of polar surface results in a decrease of ΔCp, this explains the much reduced heat capacity increase observed for DNA and emphasizes the enhanced role of polar interactions in maintaining duplex structure. Appreciation of a non-zero ΔCp for DNA has important consequences for the calculation of duplex melting temperatures (Tm). A modified approach to Tm prediction is required and comparison is made of current methods with an alternative protocol.

KW - DNA

KW - heat capacity

KW - hydration

KW - solvent accessible surface area

KW - surface polarity

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JO - European Biophysics Journal

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Thermodynamics of DNA: heat capacity changes on duplex unfolding

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