Multifaceted Analysis of the Noncovalent Interactions of Myoglobin with Finely Tuned Gemini Surfactants: A Comparative Study

This work unveils the noncovalent interactions of a novel series of finely tuned gemini surfactants (C-m-E2O-C-m = 12, 14, and 16) with myoglobin (Mb) using multifaceted spectroscopic/voltammetric and docking techniques. The Mb binding capacity of these geminis decreased in the order of C-14-E2O-C-14 > C(16)E2O-C-16 > C-12-E2O-C-12, following the 1:2 stoichiometry, as confirmed by the quantitative evaluation of binding constants via intrinsic fluorescence and cyclic voltammetry. The binding-induced microenvironmental and conformational changes of Mb were explored by pyrene/synchronous/three-dimensional (3-D) fluorescence and absorption spectroscopy. Furthermore, far- and near-ultraviolet (UV) circular dichroism spectral results depicted discernible changes in both secondary and tertiary structures of Mb upon complexation with C-m-E2O-C-m. Molecular docking specified the binding site, and aromatic residues involved in the complexation. These investigations provide deeper insight into the structure property relationships of biomacromolecules, and they will be useful in designing/selecting appropriate surfactants which, in turn, can facilitate the application of protein surfactant mixtures in pharmaceutical, biological, and industrial fields.