ISOLATION AND PARTIAL CHARACTERIZATION OF SERINE PROTEINASES PRESENT IN THE LATEX OF MACLURA-POMIFERA (OSAGE ORANGE) FRUITS

Latex provided by superficial incisions of Maclura pomifera fruits con tains several serine proteinases. Maximal activity of crude preparatio ns is reached at alkaline pH (more than 80% of maximal activity betwee n pH 9.2 and 10.8 on casein and between pH 8.0 and 9.9 on azocoll), bu t when ionic strength is higher than 0.15 M an abrupt falling of enzym e activity is noted. Thermal stability of crude preparations is a rema rkable fact, as enzyme activity is high even after 25 min at 65-degree s-C, but decreases in the case of the main purified proteolytic fracti on (III). Acetone fractionation followed by ion-exchange chromatograph y (DEAE- and CM-Sepharose CL-6B) affords four active fractions with cl osely related molecular sizes (63-71 kD, SDS-PAGE). The main proteolyt ic fraction (III, 70 kD) shows higher affinity for N-alpha-carbobezoxy -L-alanine p-nitrophenyl ester.