Abstract
The effect of the urea-class of protein denaturants on the structure of liquid water was studied. The method chosen was to monitor the microviscosity of the medium by estimating the reorientational correlation time, τ8 and proton hyperfine linewidth, WH of an inert stable organic free radical (2, 2, 6, 4-tetramethyl-piperid 4-one-l-oxyl) by measuring its electron spin resonance spectra in aqueous denaturant solutions. Urea, thiourea and guanidinium chloride were found to disrupt water structure efficiently and continuously, with the effect significant at low molarities. Dimethyl urea was found to be somewhat less efficient. The relation between the structure-breaking tendency of the denaturants and their ability to weaken hydrophobic interactions is rationalised.
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Balasubramanian, D., Ramachandran, C. Effect of protein denaturants on the structure of water: Electron spin resonance spin probe study. Proceedings of the Indian Academy of Sciences - Section B 87, 53–61 (1978). https://doi.org/10.1007/BF03178973
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DOI: https://doi.org/10.1007/BF03178973