Monitoring biomolecular interaction between folic acid and bovine serum albumin

Publication year: 2020
Authors: Chilom C.G. a, David M. b, Florescu M. b

a -  Department of Electricity, Solid Physics and Biophysics, Faculty of Physics,University of Bucharest,Măgurele, Romania, Postal address: Str.        Atomistilor no. 405, CPMG - 11, Bucuresti-Magurele, RO 077125, Romania
b  - Department of Fundamental, Prophylactic and Clinical Disciplines, Faculty of Medicine, Transilvania University of Brasov, Brasov, Romania,     Colina Universitatii no. 1, Building C, room CI30, 500068, Brasov, Romania

Published in: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020, Vol. 230, p.118074
doi: 10.1016/j.saa.2020.118074

Folic acid is a bioactive food component whose deficiency can lead to a variety of health problems, while a high intake of folic acid can reduce the cytotoxicity of natural killer cells. The binding mechanism of folic acid to free bovine serum albumin (BSA) was studied using fluorescence, while the biomolecular interaction between confined-BSA and free folic acid was assessed by electrochemical methods and surface plasmon resonance. The fluorescence quenching mechanism of BSA by folic acid was found to have a static character. The thermodynamic parameters of the interaction were determined and indicated a spontaneous exothermic process with a binding constant of 8.72 × 104 M1 at 25 °C. Confinement of BSA to gold surfaces occurred through different immobilization methods (static and hydrodynamic), inducing conformational changes, which influenced the orientation of BSA molecules binding sites towards free folic acid. The apparent binding constant using electrochemical methods (voltammetry and impedance spectroscopy) was only 5 times higher (41 and 37 × 104 M1) compared to BSA free in solution, while for surface plasmon resonance, where the hydrodynamic immobilization method was used, the value was much higher (19 × 106 M1). This work gives also an insight on the interaction of BSA with gold substrates, surface plasmon resonance enabling the calculation of the adsorbed amount. The obtained results help understanding the specific interaction between free and confined BSA with free folic acid.

MP-SPR keywords: adsorbed mass, binding, folic acid, unspecific binding to BSA