Effects of hydroxyl groups on binary diffusion coefficients of alpha-amino acids in dilute aqueous solutions

摘要

Binary diffusion coefficients, D-12, of alpha-amino acids with hydroxyl groups, e.g., serine, threonine, allothreonine and homoserine, in dilute aqueous solutions were measured at six different temperatures from 293.2 to 333.2 K by the Taylor dispersion method. The determined D-12 values of serine and threonine at 298.2 K were in good agreement with the published data, whereas no data for allothreonine and homoserine is available in the literature. The D-12 values for each amino acid were well represented with the Stokes-Einstein equation by adjusting the molecular diameter. The D-12 values for amino acids containing hydroxyl groups, except for homoserine, were lower by approximately 5%, on the basis of the same solute molar volume, than those from the corresponding amino acids without hydroxyl groups. (c) 2007 Elsevier B.V. All rights reserved.