Novel long-term storage cholesterol esterase isolated from thermotolerant Pseudomonas aeruginosa strain RE24.3

Abstract

Cholesterol esterase (CHE; EC 3.1.1.13) plays an important role in the hydrolysis of cholesterol ester to cholesterol and free fatty acids. It is used for clinical detection of cholesterol. Herein, the CHE producing microorganisms were isolated from oil contaminated soil samples at 45 °C by spreading the sample on nutritive agar. Pseudomonas aeruginosa strain RE 24.3 was selected since it produced the highest CHE activity. The purified enzyme, namely CHEPaRE24.3, had high activity between 30 and 45 °C at the optimum pH of 7.0. The substrate specificity test revealed that CHEPaRE24.3 hydrolysed a variety of cholesterol esters. Inhibitor examination found that Hg2+, β-mercaptoethanol, and DTT could inhibit me enzyme activity at 99.38%, 100%, and 43.2%, respectively. It is remarkable mat PMSF showed no effect on enzyme activity. The stability test indicated mat the CHEPaRE24.3 enzyme remained at 70% activity after 28 days storage at 4°C, 29 °C, or 37 °C. The long-term storage stability and thermotolerance of CHEPaRE24.3 as well as its resistance to PMSF suggests that it could be applicable for use in a cholesterol biosensor.