Abstract
The proteolytic enzyme from midgut epithelia of the silkworm, Bombyx mori was solubilized with Lubrol WX, partially purified and characterized. The solubilized protease coincided with digestive fluid protease-6B2 in its elution position on a Sepharose 6B column, which suggests the conversion of the former into the latter in vivo. The purified protease rapidly hydrolyzed Hammarsten casein but serum albumin very slowly. The optimum pH of this enzyme was 11.3, and Km value was estimated as 0.83 mg/ml. The protease activity was strongly inhibited by DFP, PMSF and TLCK, but not sensitive to EDTA or IAA, therefore this is conceived to be a serine-type protease having a histidine at the active site of trypsin. The tissueprotease was similar to the digestive fluid protease-6B2 in the molecular weight, substrate specificity and effect of inhibitors. Considering results, the relationship between proteases from the midgut lumen and epithelia is discussed.
