Search published articles
Showing 2 results for Residual Activity
Volume 8, Issue 30 (7-2011)
Abstract
In this study the combined effect of ultrasound and heat on inactivation of pectin methylesterase (PME) in fresh orange juice was investigated. To this end fresh orange juice was sonicated at 50, 60, 70 and 80 °C for 10, 15, 20, 25, and 30 minutes at various acoustic amplitudes and constant frequency of 30 kHz and the residual activity of PME was then measured. The results showed that ultrasound had a synergistic effect on heat resulting in an increase in the inactivation of PME. However, calculation of kinetic parameters and reaction constants indicated that increasing temperature decreased cavitation intensity and hence contribution of ultrasonic waves to PME inactivation. On the other hand, the acoustic amplitude level was found to initially increase and then diminish the rate of enzyme inactivation. In this article these changes are explained by activation parameters of DS# and DH# and possible mechanisms for ultrasonic inactivation of PME are discussed.
S. Mohseni , Kh. Khajeh, T. Tohidi Moghadam, B. Dabirmanesh, M. Haddadi,
Volume 9, Issue 3 (9-2018)
Abstract
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.
