A thermostable, alkaline-active, keratinolytic proteinase from chrysosporium keratinophilum

Abstract

Thermostable alkaline proteinase was produced by a strain of Chrysosporium keratinophilum when cultured in lactose/mineral salt medium incorporating keratin solubilized with DMSO. The proteinase, partially purified by cold-acetone precipitation followed by gel-filtration on Sephadex G-75, was optimally active at pH 9 and stable from pH 7 to 10 with over 90% relative residual activity after incubation at 25°C for 24 h. The optimum temperature for enzyme activity was 90°C at which the activity half-life was 30 min. Enzyme activity was stimulated by Fe2+ and inhibited by 1,10 o-phenanthroline. Gel-filtration indicated an Mr of 69 kDa. © 1994 Rapid Communications of Oxford Ltd.