Journal article
Solution nonideality related to solute molecular characteristics of amino acids
Biophysical journal, Vol.68(1), pp.291-302
01/1995
DOI: 10.1016/S0006-3495(95)80187-6
PMCID: PMC1281687
PMID: 7711253
Abstract
By measuring the freezing-point depression for dilute, aqueous solutions of all water-soluble amino acids, we test the hypothesis that nonideality in aqueous solutions is due to solute-induced water structuring near hydrophobic surfaces and solute-induced water destructuring in the dipolar electric fields generated by the solute. Nonideality is expressed with a single solute/solvent interaction parameter I, calculated from experimental measure of delta T. A related parameter, I(n), gives a method of directly relating solute characteristics to solute-induced water structuring or destructuring. I(n)-values correlate directly with hydrophobic surface area and inversely with dipolar strength. By comparing the nonideality of amino acids with progressively larger hydrophobic side chains, structuring is shown to increase with hydrophobic surface area at a rate of one perturbed water molecule per 8.8 square angstroms, implying monolayer coverage. Destructuring is attributed to dielectric realignment as described by the Debye-Hückel theory, but with a constant separation of charges in the amino-carboxyl dipole. By using dimers and trimers of glycine and alanine, this destructuring is shown to increase with increasing dipole strength using increased separation of fixed dipolar charges. The capacity to predict nonideal solution behavior on the basis of amino acid characteristics will permit prediction of free energy of transfer to water, which may help predict the energetics of folding and unfolding of proteins based on the characteristics of constituent amino acids.
Details
- Title: Subtitle
- Solution nonideality related to solute molecular characteristics of amino acids
- Creators
- C R Keener - Department of Radiology, University of Texas Health Science Center at San Antonio 78284-7800G D Fullerton - Department of Radiology, University of Texas Health Science Center at San Antonio 78284-7800I L Cameron - Department of Radiology, University of Texas Health Science Center at San Antonio 78284-7800J Xiong - Department of Radiology, University of Texas Health Science Center at San Antonio 78284-7800
- Resource Type
- Journal article
- Publication Details
- Biophysical journal, Vol.68(1), pp.291-302
- DOI
- 10.1016/S0006-3495(95)80187-6
- PMID
- 7711253
- PMCID
- PMC1281687
- ISSN
- 0006-3495
- eISSN
- 1542-0086
- Language
- English
- Date published
- 01/1995
- Academic Unit
- Roy J. Carver Department of Biomedical Engineering
- Record Identifier
- 9984083859302771
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