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| The effect of urea on biomimetic aggregates (aqueous and reversed micelles, vesicles and monolayers) was investigated to obtain insights into the effect of the denaturant on structured macromolecules. Direct evidence obtained from light scattering (static and dynamic), monolayer maximum isothermal compression and ionic conductivity measurements, together with indirect evidence from fluorescence photodissociation, fluorescence suppression, and thermal reactions, strongly indicates the direct interaction mechanism of urea with the aggregates. Preferential solvation of the surfactant headgroups by urea results in an increase in the monomer dissociation degree (when applied), which leads to an increase in the area per headgroup and also in the loss of... |
| Tipo: Info:eu-repo/semantics/other |
Palavras-chave: Urea; Denaturation; Surfactants; Macromolecular structure. |
| Ano: 1997 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1997000200004 |
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| Vergütz,Leonardus; Silva,Luis Henrique Mendes da; Novais,Roberto Ferreira; Silva,Maria do Carmo Hespanhol da; Mageste,Aparecida Barbosa; Silva,Ivo Ribeiro. |
| ABSTRACT Humic acids (HA) are a component of humic substances (HS), which are found in nearly all soils, sediments, and waters. They play a key role in many, if not most, chemical and physical properties in their environment. Despite the importance of HA, their high complexity makes them a poorly understood system. Therefore, understanding the physicochemical properties and interactions of HA is crucial for determining their fundamental role and obtaining structural details. Cationic surfactants are known to interact electrostatically and hydrophobically with HA. Because they are a very well-known and characterized system, they offer a good choice as molecular probes for studying HA. The objective of this study was to evaluate the interaction between... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Enthalpy; Humic substances; Isothermal titration calorimetry; Macromolecular structure; Microcalorimetry; Supramolecular structure. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000601633 |
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