Abstract
From the data of vapor pressure osmometry the activity of water, osmotic coefficients, and the values of activity coefficients of two derivatives of histidine: N-Boc-L-histidine (Boc-His-OH, m=0.005–0.14 mol⋅kg−1) and N-Boc-L-histidine-methyl ether (Boc-His-OMe, m=0.005–0.05 mol⋅kg−1) are obtained in aqueous solutions at 310.15 K. From the comparison of water activity and osmotic coefficient values it follows that Boc-His-OMe shows a more pronounced deviation from ideality than Boc-His-OH. Both components exhibit a stronger non-ideality than histidine and a weaker one than His⋅HCl. By means of potentiometric titration the acid-base properties of Boc-His-OMe are investigated and the ionization constant at 298.15 K is determined. The pK value related to the acid-base equilibrium of the nitrogen atom in the imido group of the imidazole ring is higher (6.47) than the corresponding value of histidine (6.00).
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Eisenberg, R.S.: Computing the field in proteins and channels. J. Membr. Biol. 150, 1–25 (1996)
Tsurko, E.N., Neueder, R., Kunz, W.: Water activity and osmotic coefficients in solutions of glycine, glutamic acid, histidine and their salts at 310.15 K. J. Solution Chem. 36, 651–672 (2007)
Eisenberg, B.: Ionic channels in biological membranes—electrostatic analysis of a natural nanotube. Contemp. Phys. 39, 447–466 (1998)
Eisenberg, B.: Permeation as a diffusion process. In: DeFelice, L.J. (ed.) Channels, Receptors, and Transporters. Biophysics textbook on line. http://biosci.umn.edu/biophys/OLTB/channel.html
Barthel, J., Neueder, R.: Precision apparatus for the static determination of the vapor pressure of solutions. GIT Fachz. Lab. 28, 1002–1012 (1984)
Widera, B., Neueder, R., Kunz, W.: Vapor pressures and osmotic coefficients of aqueous solutions of SDS, C6TAB and C8TAB at 25 °C. Langmuir 19, 8226–8229 (2003)
Schmidt, C.L.A., Appleman, W.K., Kirk, P.L.: The apparent dissociation constants of tryptophane and of histidine. J. Biol. Chem. 85, 137–140 (1929)
Gibbard, H.F., Scatchard, G.: Liquid—vapor equilibrium of aqueous sodium chloride, from 298 to 373 K and from 1 to 6 mol/kg, and related properties. J. Chem. Eng. Data 19, 281–288 (1973)
Pitzer, K.S., Mayorga, G.: Thermodynamics of electrolytes. III. Activity and osmotic coefficients of 2-2 Electrolytes. J. Solution Chem. 3, 539–546 (1974)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tsurko, E.N., Neueder, R. & Kunz, W. Activity of Water and Osmotic Coefficients of Histidine Derivatives in Aqueous Solutions at 310.15 K. J Solution Chem 37, 421–431 (2008). https://doi.org/10.1007/s10953-007-9237-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10953-007-9237-z