Evidence for cooperative Na + and Cl - binding by strongly hydrated l-proline

In nature the amino acid l-proline (Pro) is a ubiquitous and highly effective osmolyte protecting cells against osmotic stress. To understand this effect knowledge of the hydration of Pro and its interactions with dissolved salts is essential. We studied these properties by combining statistical mec...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2017, Vol.19 (31), p.20474-20483
Main Authors: Dmitrieva, Olga A, Fedotova, Marina V, Buchner, Richard
Format: Article
Language:English
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Summary:In nature the amino acid l-proline (Pro) is a ubiquitous and highly effective osmolyte protecting cells against osmotic stress. To understand this effect knowledge of the hydration of Pro and its interactions with dissolved salts is essential. We studied these properties by combining statistical mechanics and broadband dielectric spectroscopy and found that Pro remains strongly hydrated up to high amino-acid concentrations. This is also the case upon NaCl addition to a 0.6 M Pro solution. Here, additionally a Pro·NaCl aggregate is formed with a stability constant of K° ≈ 0.95…1.25 M , where Na and Cl cooperatively bind to adjacent carboxylate-oxygen and ammonium-hydrogen atoms, respectively.
ISSN:1463-9076
1463-9084
DOI:10.1039/c7cp04335j