抄録
Previonsly, we examined the proteases in normal and metaplastic human stomach mucosa, preparing zymograms of extract fluid from tissue with tosyl-α-lysine-α-naphthylester and α-prolyl-α-phenylalanyl-α-arginene α-naphthylester as substrates. As a result, an additional band (Rf-0.64) newly appeared in both zymograms of the metaplastic mucosa but not in those of normal mucosa. This band has also been observed with zymograms of tissue extracts of normal small intestine and gastric cancer.
In order to confirm the identity of these enzymes (Rf-0.64), which appeared in three kinds of tissue extracts, metaplastic human stomach mocosa, small intestine and gastric cancer, we purified them and examined their properties. The purified enzymes were identified as one and the same from the results of SDS-polyacrylamide gel electrophoresis and zymogram.
The molecular weight of each enzyme was found to be 55,000 and 54,000 by gel filtration on Sephadex G-200 and SDS-PAGE respectively. The effects of various inhibitors on the enzyme activities were almost the same. They were inhibited by DFP, leupeptin, Trasylol and SBTI but not by iodoacetate, EDTA, chymostain and esterastin. Moreover, the result of substrate specificities or optimum pH was almost the same with each enzyme. From these results, it was indicated that the these enzymes were the same and found to be serine protease.
Furthermore, we examined the association between intestinal metaplasia and gastric adenocarcinoma using this enzyme, detected in the preparation of the zymogram, as an indication. Examining two types of gastric cancer, the enzyme was not detected in scirrhus and other organ cancer, but only in well-differentiated adenocarcinom. This indicates that adenocarcinoma may originate from the intestinal metaplastic region.
