The Hydration of a DNA−Amphiphile Complex
Autor(a) principal: | |
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Data de Publicação: | 2004 |
Outros Autores: | , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10316/10484 https://doi.org/10.1021/jp030850b |
Resumo: | We present measurements of isothermal DNA−hexadecyltrimethylammonium (DNACTA) complex and pure DNA hydration at 25 °C using a sorption microcalorimeter. This calorimeter provides simultaneous measurement of (i) water activity (sorption isotherms) and (ii) the partial molar enthalpy of water as a function of water uptake. For pure DNA, hydration is exothermic over the studied concentration range and we find an approximately linear relation between the partial molar enthalpy and the partial molar free energy. A kink in the isotherm appears at 20.0 ± 0.3 water molecules per base pair for a water activity of 0.80, consistent with A−B transition of the DNA. There is no detectable heat effect associated with this transition. At low water contents, the hydration of the DNACTA (1:1) complex is exothermic as for the pure DNA, but after incorporation of the first 7.0 ± 0.1 water molecules, the enthalpy changes sign. At 22 water molecules per base pair, the enthalpy levels off to 2.7 ± 0.2 kJ/mol. In a separate experiment, the swelling limit for the DNACTA complex was found to be 27 ± 1 waters per base pair. The DNACTA complex is arranged in a hexagonal structure. We propose a model for the DNACTA complex based on the packing of the components in an electroneutral way consisting of six DNA helices, presumably in an A configuration, placed around a central CTA+ cylinder. The hydration of the complex is seen as a balance between the attractive electrostatic interaction causing the formation of the complex and a repulsive component arising from a hexagonal deformation of CTA+ cylinders. An important contribution to the partial molar enthalpy of water comes, in this interpretation, from the release of conformational constraints of the CTA ion alkyl chains. |
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The Hydration of a DNA−Amphiphile ComplexWe present measurements of isothermal DNA−hexadecyltrimethylammonium (DNACTA) complex and pure DNA hydration at 25 °C using a sorption microcalorimeter. This calorimeter provides simultaneous measurement of (i) water activity (sorption isotherms) and (ii) the partial molar enthalpy of water as a function of water uptake. For pure DNA, hydration is exothermic over the studied concentration range and we find an approximately linear relation between the partial molar enthalpy and the partial molar free energy. A kink in the isotherm appears at 20.0 ± 0.3 water molecules per base pair for a water activity of 0.80, consistent with A−B transition of the DNA. There is no detectable heat effect associated with this transition. At low water contents, the hydration of the DNACTA (1:1) complex is exothermic as for the pure DNA, but after incorporation of the first 7.0 ± 0.1 water molecules, the enthalpy changes sign. At 22 water molecules per base pair, the enthalpy levels off to 2.7 ± 0.2 kJ/mol. In a separate experiment, the swelling limit for the DNACTA complex was found to be 27 ± 1 waters per base pair. The DNACTA complex is arranged in a hexagonal structure. We propose a model for the DNACTA complex based on the packing of the components in an electroneutral way consisting of six DNA helices, presumably in an A configuration, placed around a central CTA+ cylinder. The hydration of the complex is seen as a balance between the attractive electrostatic interaction causing the formation of the complex and a repulsive component arising from a hexagonal deformation of CTA+ cylinders. An important contribution to the partial molar enthalpy of water comes, in this interpretation, from the release of conformational constraints of the CTA ion alkyl chains.American Chemical Society2004-03-04info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10316/10484http://hdl.handle.net/10316/10484https://doi.org/10.1021/jp030850bengThe Journal of Physical Chemistry B. 108:9 (2004) 3044-30501520-6106Leal, CeciliaWadsö, LarsOlofsson, GerdMiguel, MariaWennerström, Håkaninfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2020-02-11T18:17:36Zoai:estudogeral.uc.pt:10316/10484Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T21:01:31.842889Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
The Hydration of a DNA−Amphiphile Complex |
title |
The Hydration of a DNA−Amphiphile Complex |
spellingShingle |
The Hydration of a DNA−Amphiphile Complex Leal, Cecilia |
title_short |
The Hydration of a DNA−Amphiphile Complex |
title_full |
The Hydration of a DNA−Amphiphile Complex |
title_fullStr |
The Hydration of a DNA−Amphiphile Complex |
title_full_unstemmed |
The Hydration of a DNA−Amphiphile Complex |
title_sort |
The Hydration of a DNA−Amphiphile Complex |
author |
Leal, Cecilia |
author_facet |
Leal, Cecilia Wadsö, Lars Olofsson, Gerd Miguel, Maria Wennerström, Håkan |
author_role |
author |
author2 |
Wadsö, Lars Olofsson, Gerd Miguel, Maria Wennerström, Håkan |
author2_role |
author author author author |
dc.contributor.author.fl_str_mv |
Leal, Cecilia Wadsö, Lars Olofsson, Gerd Miguel, Maria Wennerström, Håkan |
description |
We present measurements of isothermal DNA−hexadecyltrimethylammonium (DNACTA) complex and pure DNA hydration at 25 °C using a sorption microcalorimeter. This calorimeter provides simultaneous measurement of (i) water activity (sorption isotherms) and (ii) the partial molar enthalpy of water as a function of water uptake. For pure DNA, hydration is exothermic over the studied concentration range and we find an approximately linear relation between the partial molar enthalpy and the partial molar free energy. A kink in the isotherm appears at 20.0 ± 0.3 water molecules per base pair for a water activity of 0.80, consistent with A−B transition of the DNA. There is no detectable heat effect associated with this transition. At low water contents, the hydration of the DNACTA (1:1) complex is exothermic as for the pure DNA, but after incorporation of the first 7.0 ± 0.1 water molecules, the enthalpy changes sign. At 22 water molecules per base pair, the enthalpy levels off to 2.7 ± 0.2 kJ/mol. In a separate experiment, the swelling limit for the DNACTA complex was found to be 27 ± 1 waters per base pair. The DNACTA complex is arranged in a hexagonal structure. We propose a model for the DNACTA complex based on the packing of the components in an electroneutral way consisting of six DNA helices, presumably in an A configuration, placed around a central CTA+ cylinder. The hydration of the complex is seen as a balance between the attractive electrostatic interaction causing the formation of the complex and a repulsive component arising from a hexagonal deformation of CTA+ cylinders. An important contribution to the partial molar enthalpy of water comes, in this interpretation, from the release of conformational constraints of the CTA ion alkyl chains. |
publishDate |
2004 |
dc.date.none.fl_str_mv |
2004-03-04 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10316/10484 http://hdl.handle.net/10316/10484 https://doi.org/10.1021/jp030850b |
url |
http://hdl.handle.net/10316/10484 https://doi.org/10.1021/jp030850b |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
The Journal of Physical Chemistry B. 108:9 (2004) 3044-3050 1520-6106 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
American Chemical Society |
publisher.none.fl_str_mv |
American Chemical Society |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799133906429018112 |