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

Abstract

This work unveils the noncovalent interactions of a novel series of finely tuned gemini surfactants (C m –E2O–C m , 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 C14–E2O–C14 > C16–E2O–C16 > C12–E2O–C12, 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.

Interactions of indole alkaloids with myoglobin: A mass spectrometry based spectrometric and computational method

“…In the secondary structure of proteins, α‐helix content represents the ordering of protein molecules, while β‐sheet, β‐turn and random coil reflect the looseness of protein molecules. The displacement of the chromophore absorption spectrum mainly depends on the effect of hydrophilic or hydrophobic microenvironment . Comparing the CD spectrum of Mb to that of IA–Mb solutions (Figure ), negative peaks were observed at 208 nm (π–π*) and 222 nm (n–π*).…”

“…After the addition of IA, the overall shape of CD spectra remains similar, revealing that Mb maintains its predominant α‐helix. CD intensities of all IA‐bound Mb complexes at 208 nm are higher than that of free Mb, which indicates that IA binding causes a decrease of negative ellipticity corresponding to lower α‐helical content (Table ) …”

“…The displacement of the chromophore absorption spectrum mainly depends on the effect of hydrophilic or hydrophobic microenvironment. [40][41][42] Comparing the CD spectrum of Mb to that of IA-Mb solutions ( Figure 6), negative peaks were observed at 208 nm (π-π*) and 222 nm (n-π*). This demonstrated that the secondary structure conformation of Mb was mainly α-helix, which supported the highly spiral state of Mb with a large number of α-helices in the natural state.…”

“…CD intensities of all IA-bound Mb complexes at 208 nm are higher than that of free Mb, which indicates that IA binding causes a decrease of negative ellipticity corresponding to lower α-helical content ( Table 2). 41,43 The proportions of α-helix, β-sheet, β-turn and random coil conformations were calculated and are listed in Table…”

Interaction Mechanism of Different Surfactants with Casein: A Perspective on Bulk and Interfacial Phase Behavior

“…24 Considering the absorption of aromatic heterocycles in amino acids, such as tryptophan (Trp) and tyrosine (Tyr), most protein molecules present an absorption peak near the wavelength of 270 nm. 25,26 The change in the microenvironment of aromatic amino acid residues in protein molecules will lead to shifting absorption wavelength of proteins. Thus, changes in protein structure can be preliminarily studied by using the UV−vis absorption spectra of proteins.…”