Effects of an ionic liquid as an additive on the thermal denaturation/degradation of lysozyme crystals

Abstract

Ionic liquids (ILs) have biomaterial applications and are used for protein crystallization. The present study explores the thermal denaturation and degradation kinetics of the lysozyme crystals induced by IL [C4mim]Cl using differential scanning calorimetry (DSC). Lysozyme crystals were scanned from 10 to 250 °C at different heating rates varying from 5 to 20 °C min−1. Under the same heating rate, the addition of the IL makes lysozyme crystals confer more resistance to thermal denaturation and change values of conversion rate increase. The denaturation and degradation peak shifted towards higher temperature as heating rate increased and showed an activated denaturing kinetics of the lysozyme. It can be clearly noticed that the addition of the IL increases activation energy for denaturation and decreases it for degradation. The effect of the IL on thermal denaturation is attributed to the change of lysozyme–lysozyme molecular interaction. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.

Do Ionic Liquids Exhibit the Required Characteristics to Dissolve, Extract, Stabilize, and Purify Proteins? Past-Present-Future Assessment

“…Soft anions such as formate or glycolate are superior to ILs with hard anions, like nitrate, in promoting crystallization. Wang et al reported enhanced thermal resistance of lysozyme crystals prepared in 1% [C 4 mim]­Cl, which is due to the change in lysozyme-lysozyme molecular interactions. This IL promoted the nucleation of crystals with small size, lower surface free energy, and improved morphology.…”

Practical techniques for protein crystallization: additive assistance and external field intensification

“…ILs can enhance the stability of the protein conformation and activity, 58 and even affect the renaturation of some recombinant proteins. 59 Wang et al explored the thermal denaturation and degradation kinetics of lysozyme crystals induced by ILs, 60 and lysozyme crystals were found to be more resistant to thermal denaturation in the presence of ILs. Shaposhnikova et al investigated the structural basis of the interactions between the ILs and proteins.…”