Metal-Biosurfactant Complexes Characterization: Binding, Self-Assembly and Interaction with Bovine Serum Albumin

Abstract

Studies on the specific and nonspecific interactions of biosurfactants with proteins are broadly relevant given the potential applications of biosurfactant/protein systems in pharmaceutics and cosmetics. The aim of this study was to evaluate the interactions of divalent counterions with the biomolecular anionic biosurfactant surfactin-C15 through molecular modeling, surface tension and dynamic light scattering (DLS), with a specific focus on its effects on biotherapeutic formulations. The conformational analysis based on a semi-empirical approach revealed that Cu2+ ions can be coordinated by three amide nitrogens belonging to the surfactin-C15 cycle and one oxygen atom of the aspartic acid from the side chain of the lipopeptide. Backbone oxygen atoms mainly involve Zn2+, Ca2+ and Mg2+. Subsequently, the interactions between metal-coordinated lipopeptide complexes and bovine serum albumin (BSA) were extensively investigated by fluorescence spectroscopy and molecular docking analysis. Fluorescence results showed that metal-lipopeptide complexes interact with BSA through a static quenching mechanism. Molecular docking results indicate that the metal-lipopeptide complexes are stabilized by hydrogen bonding and van der Waals forces. The biosurfactant-protein interaction properties herein described are of significance for metal-based drug discovery hypothesizing that the association of divalent metal ions with surfactin allows its interaction with bacteria, fungi and cancer cell membranes with effects that are similar to those of the cationic peptide antibiotics.

Sustainable Surfactin Production by Bacillus subtilis Using Crude Glycerol from Different Wastes

“…In brief, surfactin was isolated and purified by acid precipitation [60], namely using 6 M HCl until the pH = 2.0, and kept at 4 • C overnight. Afterward, the crude biosurfactant was pelleted by centrifugation at 9500× g for 20 min at 4 • C. Subsequently, the partially purified pellet was dissolved in deionized water, and the pH was adjusted to 7.0 using concentrated NaOH.…”

“…Surfactin stability was evaluated in a wide range of pH, temperatures and salinities, according to a previous report [61]. For the pH stability analysis, the biosurfactant solution (50 mg/L) was incubated at different pHs (2,4,6,8,10,12) at 20 • C. In turn, to investigate the temperature stability of the biosurfactant, its solution was incubated at different temperatures (20,40,60, 80 and 100 • C) at pH 6.0. Furthermore, the effect of the different salinity on surfactin activity was investigated in the range of sodium chloride concentrations from 2 to 12% (w/v) at pH 6.0 at 20 • C. All samples were kept at the defined temperature, pH and salinities for 2 h. The ST of each sample was determined as described above, and all measurements were performed in three independent experiments performed in triplicate.…”

Physiological and transcriptional profiling of surfactin exerted antifungal effect against Candida albicans

“…We hypothesize that surfactin binds to Cu 2+ ions, mimicking copper deprivation. A previous study showed that Cu 2+ ions preferentially bind to amide nitrogens of lipopeptide biosurfactants such as B. subtilis -derived surfactin (53).…”

Oxoperoxovanadium Complexes of Hetero Ligands: X‐Ray Crystal Structure, Density Functional Theory, and Investigations on DNA/BSA Interactions, Cytotoxic, and Molecular Docking Studies

“…e displacement assay was done using EtBr bound CT-DNA solution (EtBr � 10 µM and DNA � 100 µM) acting as a probe. e EtBr emission intensity was increased, 98.17 90.66 (7) when it was intercalated into DNA base pairs and the emission wavelength was 601 nm (Figure 5). In addition, by increasing the concentration of complexes (0-100 µM) gradually to EtBr-DNA, the fluorescent intensity decreased due to the displacement of EtBr by complexes [63][64][65].…”

“…Because of its capacity to bind reversibly to a wide range of molecules, it is considered the major transporter of regulatory mediators, metabolic products, nutrients, and fatty acids. Through hydrogen bonding, hydrophobic, and electrostatic interactions, serum albumin neutralizes endogenous and external poisons [ 7 , 8 ]. Several metal complexes are known to exert their anticancer action through effective binding with nucleases and proteins.…”