Comparison of the binding behavior of FCCP with HSA and HTF as determined by spectroscopic and molecular modeling techniques

Abstract

The interaction of carbonylcyanide p-(trifluoromethoxy) phenylhydrazone (FCCP) with human serum albumin (HSA) and human transferrin (HTF) was investigated using multiple spectroscopy, molecular modeling, zeta-potential and conductometry measurements of aqueous solutions at pH 7.4. The fluorescence, UV/vis and polarization fluorescence spectroscopy data disclosed that the drug-protein complex formation occurred through a remarkable static quenching. Based on the fluorescence quenching, two sets of binding sites with distinct affinities for FCCP existed in the two proteins. Steady-state and polarization fluorescence analysis showed that there were more affinities between FCCP and HSA than HTF. Far UV-CD and synchronous fluorescence studies indicated that FCCP induced more structural changes on HSA. The resonance light scattering (RLS) and zeta-potential measurements suggested that HTF had a greater resistance to drug aggregation, whereas conductometry measurements expressed the presence of free ions improving the resistance of HSA to aggregation. Thermodynamic measurements implied that a combination of electrostatic and hydrophobic forces was involved in the interaction between FCCP with both proteins. The phase diagram plots indicated that the presence of second binding site on HSA and HTF was due to the existence of intermediate structures. Site marker competitive experiments demonstrated that FCCP had two distinct binding sites in HSA which were located in sub-domains IIA and IIIA and one binding site in the C-lobe of HTF as confirmed by molecular modeling. The obtained results suggested that both proteins could act as drug carriers, but that the HSA potentially had a higher capacity for delivering FCCP to cancerous tissues.

Spectrophotometric and molecular modelling studies on in vitro interaction of tyrosine kinase inhibitor linifanib with bovine serum albumin

“…In addition to albumin the drug ligands also bind to other proteins such as human holo-transferrin. These proteins act as carriers for these drugs to the site of action [16, 17]. …”

Studies on the interaction between promethazine and human serum albumin in the presence of flavonoids by spectroscopic and molecular modeling techniques

“…The decrease of α-helix percentage indicates that the PMT molecules bind with the amino acid residues of main polypeptide chain and partly destroy the hydrogen bonding networks of the protein [73]. The result indicates that the interaction between PMT and HSA causes the slight unfolding of the polypeptide and conformational changes of HSA.…”

Nonenzymatic glycosylation of human serum albumin and its effect on antibodies profile in patients with diabetes mellitus

“…Another study done by Ahmadi et al In 2014, uses fluorescence, CD and UV spectroscopic techniques to demonstrates the complex formation between β-lactoglobulin and retinol at interplay of hydrophobic interactions [48]. Previous study uses spectroscopic approach to demonstrate the interaction between human serum albumin and carbonyl cyanide p- (trifluoromethoxy) phenylhydrazone (FCCP) [49]. In another study done on HSA interaction, fluorescence spectroscopy and zeta potential was used to decipher complex formation [50].…”