Cloning, Expression, Purification and Enzymatic Characterization of Low-temperature Cholesterol Esterase from Marine <i>Panthenia Agglutinosa</i>

BACKGROUND: The low-temperature cholesterol esterase is primarily used in industries such as papermaking and healthcare. OBJECTIVE: To discover a microorganism with high cholesterol esterase activity and tolerance to low temperatures, leading to the promotion of the sustainable utilization of marine cold-adapted microbial resources and fostering industrial development. MATERIALS AND METHODS: This study isolated a strain producing low-temperature cholesterol esterase from marine samples in the China Bohai Sea. The strain was identified through 16S rDNA sequencing and named Panthenia agglutinosa Y03. The cholesterol esterase gene (PaChe) from P. agglutinosa Y03 was cloned and heterologously expressed in Escherichia coli , and the recombinant enzyme PaChe was purified and characterized. The structure of PaChe was predicted using AlphaFold2, and molecular docking was performed with cholesterol linoleate as the ligand. RESULTS: The enzyme protein has a molecular weight of 56.35 KDa, a theoretical pI of 7.24, lacks a signal peptide, and exhibits structural features of the α/β hydrolase superfamily protein. The concentration of the purified PaChe is 0.5 mg/mL, with a specific activity of 42.7 U/mg. The optimal working temperature is 30 °C, and the enzyme retains activity at 4 °C , demonstrating weaker thermal stability. The optimal pH is 7, and the enzyme maintains over 70% activity at pH 9. Na +, Ca 2+ and Mg 2+ are the primary activators, while Ba 2+ , Fe 2+ , Mn 2+ , Cu 2+ and chemical agents such as SDS as inhibitors, with Cu 2+ exhibiting particularly significant inhibitory effects. CONCLUSION: This study establishes the theoretical groundwork for the development and utilization of a novel lowtemperature cholesterol esterase.