Study on the interaction between surfactin and alkaline protease in aqueous solution.

Area of Science:

• Biochemistry
• Protein-ligand interactions

Background:

• Alkaline protease is a crucial enzyme with broad industrial applications.
• Surfactin, a lipopeptide biosurfactant, can interact with proteins, potentially modulating their activity.

Purpose of the Study:

• To investigate the molecular interactions between surfactin and alkaline protease in aqueous solution.
• To elucidate how surfactin affects the structure and enzymatic activity of alkaline protease.

Main Methods:

• Ultraviolet-visible (UV-vis) absorption spectroscopy
• Fluorescence spectroscopy
• Fourier transform infrared spectroscopy (FTIR)
• Enzyme activity assays
• Particle size and Zeta potential measurements
• Surface tension measurements

Main Results:

• Surfactin binding caused alkaline protease peptide chain extension and altered conformation, weakening hydrophobic interactions.
• FTIR confirmed weak interactions, primarily hydrogen bonds, between surfactin and alkaline protease.
• Enzyme activity was enhanced at low surfactin concentrations and inhibited at high concentrations.
• Surfactin concentration influenced system particle size and Zeta potential, indicating electrostatic interactions.
• Surface tension data suggested spontaneous binding between surfactin and alkaline protease molecules.

Conclusions:

• Surfactin significantly interacts with alkaline protease, affecting its conformation and activity.
• The interaction is concentration-dependent, with a dual effect on enzyme activity.
• A composite model for surfactin-alkaline protease interaction in aqueous solution was proposed based on the findings.