Systematic search for novel proteinases in gastrointestinal tract and studies on their physiological roles and structure/function

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1.A novel membrane-bound serine proteinase degrading vasoactive intestinal polypeptide fairly specifically and a novel membrane-associated intracellular trypsin were isolated from porcine gastric antral mucosa and characterized.2.Enteropeptidase cDNA was isolated and cloned from the cDNA library of rat duodenum and its primary structure was deduced. In addition, the tissue distributionof its mRNA was analyzed.3.A novel membrane-associated metalloproteinase degrading progastrin peptide fairly specifically was isolated from porcine brain and characterized.4.The microsomal membrane-bound serine proteinase from rat liver was identified as hepsin from analyzes of its polypeptide chain composition and partialamino acid sequence.5.Pepsinogen isoforms were isolated and characterized from the gastric mucosae of turtle and tuna stomach and the amino acid sequences of their major forms were determined.6.Normal human blood alpha _2-macroglobulin was shown to contain a small but significant amount of novel serine proteinase (s) naturally entrapped in it.7.Pancreatic trypsin and alpha-chymotrypsin were shown to selectively cleave Arg-X and Phe-X bonds, respectively, at a high alkaline pH (pH-13).8.In relation to this project, additional characterization studies were performed on some other proteinases including follipsin, prolylendopeptidase, acid proteinase B,and signal peptidase and bromelain inhibitors.