Solubility of the Proteinogenic ?-Amino Acids in Water, Ethanol, and Ethanol-Water Mixtures.

ABSTRACT: The addition of organic solvents to ?-amino acids in aqueous solution could be an effective method in crystallization. We reviewed the available data on the solubility of ?-amino acids in water, water-ethanol mixtures, and ethanol at 298.15 K and 0.1 MPa. The solubility of l-alanine, l-proline, l-arginine, l-cysteine, and l-lysine in water and ethanol mixtures and the solubility of l-alanine, l-proline, l-arginine, l-cysteine, l-lysine, l-asparagine, l-glutamine, l-histidine, and l-leucine in pure ethanol systems were measured and are published here for the first time. The impact on the solubility of amino acids that can convert in solution, l-glutamic acid and l-cysteine, was studied. At lower concentrations, only the ninhydrin method and the ultraperfomance liquid chromatography (UPLC) method yield reliable results. In the case of ?-amino acids that convert in solution, only the UPLC method was able to discern between the different ?-amino acids and yields reliable results. Our results demonstrate that ?-amino acids with similar physical structures have similar changes in solubility in mixed water/ethanol mixtures. The solubility of l-tryptophan increased at moderate ethanol concentrations.

SUBMITTER: Bowden NA 

PROVIDER: S-EPMC5846082 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature