Changes in optical rotation of some α-amino acids are induced by electrolytes. Such effects on L- and D-enantiomers of a range of amino acids are explored for sodium salts with varying anion. The amino acids studied were alanine, aspartic acid, glutamic acid, glutamine, proline, threonine, and tryptophan. The anion's polarizability in soln. accounts for the change in [α] only for the halides. Self-assocn. of amino acids in soln. and pH changes due to the presence of the electrolytes do not account for the obsd. variations in optical activity. Specific interactions of anions with the chiral amino acids (Hofmeister effects) and salt-induced perturbations of the amino acid hydration shell appear to be responsible for the effects, and conformational changes in the chiral solutes due to the presence of ionic species are discussed.
Specific Anion Effects on the Optical Rotation of α-Amino Acids / Rossi, S.; LO NOSTRO, Pierandrea; Lagi, M.; Ninham, B. W.; Baglioni, Piero. - In: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL. - ISSN 1520-6106. - STAMPA. - 111:(2007), pp. 10510-10519. [10.1021/jp0721806]
Specific Anion Effects on the Optical Rotation of α-Amino Acids
LO NOSTRO, PIERANDREA;BAGLIONI, PIERO
2007
Abstract
Changes in optical rotation of some α-amino acids are induced by electrolytes. Such effects on L- and D-enantiomers of a range of amino acids are explored for sodium salts with varying anion. The amino acids studied were alanine, aspartic acid, glutamic acid, glutamine, proline, threonine, and tryptophan. The anion's polarizability in soln. accounts for the change in [α] only for the halides. Self-assocn. of amino acids in soln. and pH changes due to the presence of the electrolytes do not account for the obsd. variations in optical activity. Specific interactions of anions with the chiral amino acids (Hofmeister effects) and salt-induced perturbations of the amino acid hydration shell appear to be responsible for the effects, and conformational changes in the chiral solutes due to the presence of ionic species are discussed.File | Dimensione | Formato | |
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