Characterization of lactate–guanidinium and lactate–lactate interactions in aqueous solution by spectropolarimetry

Abstract

Spectropolarimetry has been used to quantify the lactate–guanidinium and lactate–lactate equilibrium interactions in aqueous solution. Association constants for the lactate–guanidinium and lactate–lactate formations are 6.11 dm³ mol^–1 and 1.12 dm³ mol^–1, respectively, in aqueous solution; 6.11 dm³ mol^–1 is a high value for an electrostatic interaction in water. This stability, however, cannot account for the extremely strong lactate–protein binding, observed earlier by NMR spectroscopy. The molar rotation coefficients for both the heteroassociation and homoassociation complexes are also calculated.

The homoassociative lactate–lactate binding is the first such interaction, whose constant has been determined by spectropolarimetry in aqueous solution.