Viscosities and apparent molar volumes of some amino acids in water and in 6M guanidine hydrochloride at 25°C

Prantner

Analytical Biochemistry

2008

Capillary electrophoresis has been used to determine whether zwitterions contribute to the ionic strength of a solution, by measuring the mobility of a double-stranded DNA oligomer in cacodylatebuffered solutions containing various concentrations of the ionic salt tetraethylammonium chloride (TEA + Cl − ) or the zwitterion tricine +/− . The mobility of the DNA decreased as the square root of ionic strength, as expected by the Debye-Hückel-Onsager theory of electrophoresis, when TEA + Cl − was added to the buffer. However, the mobility was independent of the concentration of added tricine +/− . Hence, zwitterions do not contribute to the ionic strength of a solution. KeywordsZwitterions; ionic strength; DNA; capillary electrophoresis Very few experiments have been designed to directly test whether zwitterions contribute to the ionic strength of a solution. However, capillary electrophoresis measurements in free solution are ideal for this purpose. If an analyte, such as a small DNA oligomer, does not bind one of the ions in the background electrolyte, its electrophoretic mobility will decrease as the square root of ionic strength [ 9 ], as predicted by Debye-Hückel-Onsager theory of electrophoresis [ 10 ], regardless of whether the ionic strength is increased by increasing the buffer concentration or by adding a neutral salt to the buffer. The same result would be expected upon adding a zwitterion to the buffer, if zwitterions contribute to the ionic strength. By contrast, if a zwitterion does not contribute to the ionic strength (and does not bind to the analyte), the observed mobility will be independent of the concentration of the added zwitterion.Capillary electrophoresis experiments were therefore carried out using a random-sequence, 26 base-pair double-stranded DNA oligomer with the sequence 5′-CGCTTACTAGATACTACTAGTACTAG-3′, called ds26 for brevity, as the analyte. The duplex, which was prepared by standard methods from single-stranded oligomers synthesized by Integrated DNA Technologies (Coralville, IA), was monodisperse when analyzed by polyacrylamide gel electrophoresis. The capillary zone electrophoresis experiments were * Corresponding author. Tel: +319-335-7896; Fax: +319-335-9570; Email address: nancy-stellwagen@uiowa.edu (N.C. Stellwagen). a Present address: Department of Chemistry, University of Washington, Seattle, WA 98915.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Since relatively high concentrations of TEA + Cl − and tricine +/− were used in some of the experiments, the increased viscosity of solutions containing high concentrations of added...

mentioning

confidence: 57%

Do zwitterions contribute to the ionic strength of a solution?

Prantner

Analytical Biochemistry

2008

“…Salt-induced electrostatic forces are known to play a crucial role in modifying the protein structure [3] by affecting properties such as solubility, denaturation, etc., as mentioned earlier [1,2] in widely different manners. It is well established that various co-solutes and co-solvents such as guanidine hydrochloride [4,5], potassium thiocyanate [6], potassium chloride [7], tetraalkylammonium salts [8,9], etc., can act as effective probes of their conformation in solutions [10][11][12][13].…”

mentioning

confidence: 99%

“…Thus, thermodynamic properties of amino acids in aqueous electrolyte solutions provide valuable information about solute-solvent and solute-solute interactions. Hence, there have been extensive studies [4][5][6][7][8][9][18][19][20] to reveal the effect of electrolytic solutions on amino acids. But to the best of our knowledge, such studies in aqueous Ag 2 SO 4 solutions are rarely reported in the literature except for our previous work with glycine [21].…”

mentioning

confidence: 99%

Physicochemical Properties of L-Alanine in Aqueous Silver Sulphate Solutions at (298.15, 308.15, and 318.15) K

et al. 2011

Apparent molar volumes (ϕ V ) and viscosity B coefficients for l-alanine in (0.005, 0.010, 0.015, and 0.020) mol · dm −3 aqueous silver sulphate (Ag 2 SO 4 ) solutions were determined from the solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of amino acid concentration. The standard partial molar volumes (ϕ 0 V ) and experimental slopes (S * V ) obtained from the Masson equation were interpreted in terms of solute-solvent and solute-solute interactions, respectively. To analyze solution viscosities in terms of viscosity B coefficients, the Jones-Dole equation was applied. The structure-making or -breaking ability of the amino acid has also been discussed in terms of the sign of (δ 2 ϕ 0 V /δT 2 ) P . The activation parameters of viscous flow for the ternary solutions were also derived and explained in terms of transition state theory.

“…The values of transfer volumes, V φ 0 tr are negative and decrease monotonically (Figure 2) with the molal concentration of paracetamol and increase with temperature are shown in table 2. The value of V φ 0 tr is theoretically free from solute-solute interaction and it provides information regarding solute-solvent interactions [37]. The negative value V φ 0 tr for the alanine in aqueous paracetamol solutions could be explained by the co-sphere overlap model developed by Friedman and Krishnan [38].…”

confidence: 99%

Studies on Volumetric and Viscometric Properties of Alanine in Aqueous Paracetamol Solution Over a Range of Temperature (298.15 to 318.15) K.

2017

IJAERD