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Specific anion effects on the optical rotation of glucoseand serine
Author(s) -
Nostro Pierandrea Lo,
Ninham Barry W.,
Milani Silvia,
Fratoni Laura,
Baglioni Piero
Publication year - 2005
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.20389
Subject(s) - chemistry , optical rotation , ion , polarizability , hofmeister series , molecule , electrolyte , chemical physics , fourier transform infrared spectroscopy , membrane , inorganic chemistry , organic chemistry , chemical engineering , biochemistry , electrode , engineering
Optical activity is directly related to molecular conformation through the anisotropic polarizabilities of molecules and the refractive index of materials. L ‐amino acids and D ‐sugars are characteristic essential bioactive molecules. Since molecular recognition and enzyme activity are related to the conformation of substrates, the relevance of optical activity to biological processes is evident. Specific ion, or Hofmeister, effects that occur with electrolytes at moderately high concentrations modify the behavior of interfaces, molecular forces between membranes, of bulk solutions, of enzymes, and even of DNA. Such effects are universal. Here we report a study on the change in optical rotation induced by some sodium salts for the enantiomers of serine and glucose in water solution. The optical rotation is shown to depend on the kind of anion and on the salt concentration. To obtain further insights into the mechanism behind the phenomenon, Fourier transform infrared (FTIR) spectral studies of serine and glucose solutions in electrolytes were also carried out. The results suggest that it is the differences in interactions of anions at specific chemical sites of the solutes that are responsible for the effects. These forces depend strongly on anion polarizability in water. Such specific ion preferential interactions can affect conformation and internal field, and result in significant changes in optical rotation. © 2005 Wiley Periodicals, Inc. Biopoly 81: 136–148, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com