Leupeptins, New Protease Inhibitors From Actinomycetes

Antiplasminactivity of culture nitrates of actinomycetes were examined and the active compounds were isolated.The compounds were acetyl-or propionyl-L-leucyl-L-leucyl-DL-argininal, and their analogues which contained isoleucine or valine instead of one or two leucines and they were named leupeptins.Ten strains which produced leupeptins were examined in detail and classified as follows: the strains MA839-A1, MB262-M1, Streptomyces