Purification and Characterization of Digitaria exilis Protease (White Acha)

The protease of malted Digitaria exilis (white acha) species was extracted, purified and characterized. The enzyme was extracted with 200 ml of 0.1M citrate phosphate buffer (pH 7) containing 0.4% (w/v) cysteine and 0.86% NaCl, purified by dialysis against 4M sucrose, Ion exchange chromatography on CM sepharose and gel filtration chromatography on Sepharose 4B gel. On ion exchange chromatography and gel filteration chromatography, the white acha protease was purified 2.21 folds with a specific activity of 362 Umg-1 protein. The relative molecular weight of the protease was estimated to be 88,000 daltons by Gel filtration. The white acha protease was optimally active at 50oC and pH 7, but retained about 40% of its activity at 70oC (30 mins) and pH 8. Appreciable stimulation (P