Aims: Matrix Metalloproteinase 9 (MMP-9) plays an important role in the development of many diseases such as periodontitis, atherosclerosis, and cancer.  One of the methods for stability of enzyme is using deep eutectic solvents (DESs). The aim of this study was to investigate the effect of deep eutectic solvent on stability and structure of Matrix Metalloproteinase 9 with therapeutic purpose.
Materials and Methods: Herein, active full length recombinant human MMP-9 (amino acid residues 107-707) was expressed in Escherichia coli BL21, using the vector pET21a, and purification and refolding were conducted, using urea gradient method on Ni-NTA column, simultaneously. The effect of DES based on choline chloride and glycerol with a 1:1 mol ratio was investigated on activity, stability, and structure of MMP-9. The enzyme activity at different concentrations of gelatin in the presence of 15% and 30% volume/volume DESs at pH 7.8 was investigated for obtaining Vmax and km by Michaelis-Menten kinetics, using the Prism 5.0 software.
Findings: With an increase in the percentage of solvents up to 30%, the specific activity of enzyme increased, followed by a decreasing trend, and in the presence of a 30% volume/volume solvent at a temperature of 50°C and 60°C, compared with a 15% solvent and no solvent, contained more residue activity. The results showed more solubility of enzyme in 30% solvent.
Conclusion: MMp-9 has the highest activity in presence of 30% volume/volume DES based on choline chloride and glycerol. Increase in thermal stability of MMp-9 can be attributed to compactness of structure in the presence of DES.