Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An erythrocyte membrane-associated cathepsin D-like acid proteinase, termed "EMAP," was purified to homogeneity from freshly collected rat blood in a yield of 60-65%. The molecular weight of the enzyme was determined to be 80,000-82,000 by Sephadex G-100 gel filtration. The enzyme was inhibited strongly by pepstatin and partially by HgCl2, Pb(NO3)2, and iodoacetic acid. The preferred substrate for the enzyme was hemoglobin. The enzyme also hydrolyzed serum albumin and casein, but to lesser extents, with an optimum pH of 3.5-4.0. However, it could not hydrolyze leucyl-2-naphthylamide, benzyloxycarbonyl-Phe-Arg-4-methyl-7-coumarylamide or other synthetic substrates at pH values ranging from 3.5 to 9.5. The enzyme was very similar to human EMAP in a number of enzymatic properties, whereas it differed from rat cathepsin D in several respects, such as pH stability, molecular weight, isoelectric point, and chromatographic properties. Immunologically, the enzyme cross-reacted with the rabbit antibody prepared against human EMAP. The patterns of immunoelectrophoresis, immunoblotting, and immunoprecipitation of the enzyme were remarkably similar, if not identical, to those of human EMAP. In contrast, rat EMAP showed no reaction with the rabbit antibody raised to rat spleen cathepsin D. These results indicate that EMAP is a unique cathepsin D-like acid proteinase different from ordinary cathepsin D.
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PMID:Isolation, and catalytic and immunochemical properties of cathepsin D-like acid proteinase from rat erythrocytes. 354 79

An acid proteinase purified from human erythrocyte membranes (Yamamoto, K. & Marchesi, V.T. (1984) Biochem. Biophys. Acta 790, 208-218), now termed "EMAP," was further characterized with respect to its localization and relation to cathepsin D. The membrane-associated form of EMAP was shown to be latent by demonstrating that no activity was detectable in both resealed (right-side-out) ghosts and inside-out vesicles in the absence of detergents. The enzyme associated with the inside-out vesicles was unstable when exposured to acidic pH between 4.0 and 4.5, whereas the enzyme associated with the resealed ghosts was stable in the wide pH range of 3.7 to 9.0. Tryptic digestion produced the loss of activity for the enzyme associated with the inside-out vesicles but not the resealed ghosts. The antibody to rat spleen cathepsin D, which cross-reacted weakly but detectably with EMAP, selectively bound to the inside-out vesicles. These results indicate the location of EMAP on th inner surface of the membranes. Comparison of a number of enzymatic properties of EMAP with rat cathepsin D showed significant differences between these two enzymes. EMAP was less stable in the pH range of 3.5 to 6.0 than cathepsin D. The enzymes were distinguished from each other by differences in their elution profiles on DEAE-Sephacel and chromatofocusing columns and by differences in the extent of inhibition by a few specific inhibitors. Both enzymes revealed significant differences in the amino acid composition and specific activity towards bovine hemoglobin. The immunological relationship between these two enzymes is discussed.
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PMID:Human erythrocyte membrane acid proteinase (EMAP): sidedness and relation to cathepsin D. 392 57