Proteases have applications in food, detergent and pharmaceutical industries. A novel protease has been purified from the latex of Calotropis procera and characterized. As another cysteine protease, procerain, is reported from the same source, the newly purified enzyme was named as procerain B. The enzyme shows distinct properties compared to procerain, in terms of cleavage recognition site, immunological properties and other physical properties like molecular weight, isoelectric point, etc. The newly purified enzyme shows a broad optimum pH (6.5-8.5) as well as broad optimum temperature (40-60 degrees C). Additionally, the enzyme retains its activity where most of other proteases are not active. Moreover, the enzyme appeared to be very efficient in hydrolysis of blood stain and may have potential application in detergent industries. Simple and economic purification of procerain B, together with easy availability of latex, makes the large-scale production of procerain B possible, thus enables to explore various industrial as well as biotechnological applications. (C) 2009 Elsevier Ltd. All rights reserved.