PARTIAL INACTIVATION OF MICROBIAL PROTEINASES WITH SOYBEAN KUNITZ ANDBOWMAN-BIRK INHIBITORS

It was previously demonstrated that some plant inhibitors are able to inactivate the bacterial proteinase subtilisin; since information conc erning the effect of plant inhibitors on other microbial proteinases r emains limited, we decided to determine the activity of the soybean Ku nitz and Bowman-Birk inhibitors (KI and BBI, respectively) on 14 prote inases of fungal and bacterial origin. The results show that microbial proteinases are frequently inhibited by KI and BBI and that proteinas es with the same EC number leg subtilisin Carlsberg and subtilisin BPN ') may equally give different responses to the inhibitors. In particul ar, all serine proteinases examined were affected by both KI and BBI w hile metalloproteinases were not. Inhibition was also achieved on a ra nge of microbial proteinases for which the mechanistic class is yet to be established; the data suggest that they belong to the serine type. In one instance, activation instead of inhibition was noted.