Engineering a thermo-stable superoxide dismutase functional at sub-zero to >50°C, which also tolerates autoclaving

Superoxide dismutase (SOD) is a critical enzyme associated with controlling oxygen toxicity arising out of oxidative stress in any living system. A hyper-thermostable SOD isolated from a polyextremophile higher plant Potentilla atrosanguinea Lodd. var. argyrophylla (Wall. ex Lehm.) was engineered by mutation of a single amino acid that enhanced the thermostability of the enzyme to twofold. The engineered enzyme was functional from sub-zero temperature to >50°C, tolerated autoclaving (heating at 121°C, at a pressure of 1.1 kg per square cm for 20 min) and was resistant to proteolysis. The present work is the first example to enhance the thermostability of a hyper-thermostable protein and has potential to application to other proteins for enhancing thermostability.