Binding modes of three inhibitors 8CA, F8A and I4A to A-FABP studied based on molecular dynamics simulation

Adipocyte fatty-acid binding protein (A-FABP) is an important target of drug designs treating some diseases related to lipid-mediated biology. Molecular dynamics (MD) simulations coupled with solvated interaction energy method (SIE) were carried out to study the binding modes of three inhibitors 8CA, F8A and I4A to A-FABP. The rank of our predicted binding affinities is in accordance with experimental data. The results show that the substitution in the position 5 of N-benzyl and the seven-membered ring of N-benzyl-indole carboxylic acids strengthen the I4A binding, while the substitution in the position 2 of N-benzyl weakens the F8A binding. Computational alanine scanning and dynamics analyses were performed and the results suggest that the polar interactions of the positively charged residue R126 with the three inhibitors provide a significant contribution to inhibitor bindings. This polar interaction induces the disappearance of the correlated motion of the C terminus of A-FABP relative to the N terminus and favors the stability of the binding complex. This study is helpful for the rational design of potent inhibitors within the fields of metabolic disease, inflammation and atherosclerosis.