Use of the Walden Product to evaluate the effect of amino acids on water structure.
The Walden Product, the product of viscosity (eta 0) and conductivity at infinite dilution of a solution (lambda 0), provides a measurement of the water-structuring activity of the solute. Measuring the effect of concentration on viscosity of solutions of amino acids, together with the conductivity of solutions of sodium chloride containing increasing concentrations of the amino acids, enabled Walden Products to be determined. The classical form of the Walden Product (lambda 0 eta 0) was used, together with a modified form, lambda 0 eta c, in which eta c was the slope of the concentration/viscosity curve. Most amino acids demonstrated modest water-structure-breaking activity but L-lysine, L-glutamic acid and L-aspartic acid, and their respective salts, all showed relatively higher activity. Dextrose behaved as a classical water-structure maker and, when added progressively, reversed the breaking activity of L-lysine. It is speculated that effects seen in bulk water may also occur at emulsion droplet surfaces, thereby inducing structural changes associated with the occasional rapid instability experienced when making admixtures of phospholipid-stabilized emulsions and additives such as amino acids and dextrose.
Lutz
O
O
Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago 60607.
Vrachopoulou
M
M
Groves
M J
MJ
D000596:Amino Acids / Q000737:chemistry*; D003217:Conductometry; D009994:Osmolar Concentration; D014783:Viscosity; D014867:Water / Q000737:chemistry*
D000596:Amino Acids; D014867:Water