Binding between bovine serum albumin (BSA) and a plumeran indole alkaloid (PIA) isolated from the stem bark of Aspidosperma cylindrocarpon (Apocynaceae) was studied by spectroscopic techniques (UV-Vis absorption, circular dichroism, steady state and time-resolved fluorescence), combined with molecular docking. Steady state and time resolved fluorescence data revealed that PIA can quench the BSA fluorescence via a static mechanism: energy transfer from BSA to PIA occurs with high probability.
The binding is strong (Kb ca. 105-106 L mol-1), spontaneous (ΔG° ca. -35.7 kJ mol-1 at 310 K) and entropy-driven (ΔS° = 0.146 kJ mol-1 K-1). There is just one main binding site (n ca. 1) for the BSA:PIA interaction and the α-helix content of the albumin does not suffer significant perturbation upon PIA binding. Molecular docking results suggest site I as the main binding site to PIA, which is able to interact with the Trp-212, Arg-217, Val-342 and Pro-446 residues.
Chaves, O.A., Teixeira, F.S., Guimarães, H.A., Braz-Filho, R., Vieira, I.J.C., Sant'Anna, C.M.R., Netto-Ferreira, J.C., Cesarin-Sobrinho, D. and Ferreira, A.B., 2017. Studies of the interaction between BSA and a plumeran indole alkaloid isolated from the stem bark of Aspidosperma cylindrocarpon (Apocynaceae). Journal of the Brazilian Chemical Society, 28(7), pp.1229-1236.
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