Osmolyte-specific counteraction of ethanol-induced aggregation and structure-function distortion of catalase

Abstract

Catalase, an industrially important enzyme, was found to unfold and aggregate in presence of ethanol. Aggregation of catalase was observed in 20% and higher ethanol concentrations as evident by typical light scattering aggregation profile with complete absence of lag phase, enhanced Thioflavin T fluorescence, increased 8-anilinonaphthalene-1-sulfonic acid binding depicting enhanced hydrophobic exposure, unfolded tertiary structure with an altered Fourier transform infrared and soret spectra. To prevent ethanol-induced aggregation of catalase, osmolytes were screened for their ability to counteract the ethanol effects on catalase. Among all the osmolytes tested, only three i.e., betaine, trehalose and sucrose counteracted the ethanol-induced aggregation of catalase by about 30–50%. Results infer that addition of osmolytes to ethanol-treated catalase persuaded changes in solvent polarity and protein microenvironment leading to overall counteraction of ethanol-induced structural changes in catalase responsible for its aggregation. Fluorescence microscopy also confirmed the counteraction of ethanol-induced aggregation by osmolytes as evident from the decreased presence of aggregates in osmolyte-incubated ethanol-treated catalase. Overall, the osmolyte-induced counteraction of ethanol effects on catalase is biologically significant as it provides significant insights regarding the prevention of organic solvent induced aggregation of industrially important enzymes, being otherwise vulnerable to the solvent-induced distortion of their structure-function integrity.