Multispectroscopic studies of the interaction of folic acid with glycated human serum albumin.

The interaction between glycated human serum albumin (gHSA) and folic acid (FA) was investigated by various spectroscopic techniques, such as fluorescence, circular dichroism, UV-vis absorption spectroscopy and electrophoretic light scattering technique. These methods characterize the binding properties of an albumin-folic acid system. The binding constants values (Ka) at 300 and 310 K are about 104 M-1. The standard enthalpy change (ΔH) and the standard entropy change (ΔS) were calculated to be ∼-20 kJ mol-1 and ∼16 J mol-1 K-1, respectively, which indicate characteristic electrostatic interactions between gHSA and folic acid. The CD studies showed that there are no significant conformational changes in the secondary structure of the protein. Moreover, the zeta potential measurements proved that under physiological conditions the gHSA-folic acid complex shows instability. No significant changes in the secondary structure of the protein and reversible drug binding are the desirable effect from pharmacological point of view. Communicated by Ramaswamy H. Sarma.