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)

Two kinds of cathepsin D were found in Japanese monkey lung and were named cathepsins D-I and D-II. Cathepsin D-I was partially purified by ammonium sulfate fractionation and DEAE-cellulose column chromatography. It had properties common to other ordinary cathepsins D in terms of the elution position from a DEAE-cellulose column at pH 8.0, the pH-dependence of activity toward acid-denatured hemoglobin, and the molecular weight of 35,000 as determined by Sephadex G-100 gel filtration. On the other hand, cathepsin D-II was purified about 1,000-fold by a combination of ammonium sulfate fractionation and column chromatographies on DEAE-cellulose and Sephadex G-100. It was a very acidic protein as judged from its elution position from a DEAE-cellulose column at pH 8.0, and the high mobility toward the anode on disc gel electrophoresis at pH 8.6. Its molecular weight was determined to be 35,000 by Sephadex G-100 gel filtration and 39,000 by SDS-polyacrylamide gel electrophoresis. It was optimally active at pH 2.8 against acid-denatured hemoglobin as a substrate, showing 80% of the optimal activity at pH 1.0, and almost no activity above pH 4.0. This pH-profile of activity was similar to that of monkey pepsin C (gastricsin). It did not hydrolyze N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine, a synthetic substrate for pepsin, but was inhibited by a series of pepsin inhibitors such as pepstatin, 1,2-epoxy-3-(p-nitrophenoxy)propane, p-bromophenacyl bromide, and diazoacetyl-DL-norleucine methyl ester, although the diazo reagent was a rather weak inhibitor of the enzyme. The amino acid composition of cathepsin D-II was found to be fairly different from those of other cathepsins D. However, it showed a striking resemblance to that of Japanese monkey pepsinogen C, suggesting some evolutionary relationship between them.
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PMID:The structure and function of acid proteases. VIII. Purification and characterization of cathepsins D from Japanese monkey lung. 2 23

1. Three pepsins were purified from the gastric mucosa of Atlantic cod (Gadus morhua). 2. The enzymes, called Pepsin I and Pepsin IIa and b, had isoelectric points 6.9, 4.0 and 4.1, respectively, and digested hemoglobin at a maximal rate at a pH of approximately 3. 3. They resembled bovine cathepsin D in being unable to digest the mammalian pepsin substrate N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine. 4. Specificity constants (kcat/Km) for the cod pepsins were lower than for porcine pepsin, and they expressed higher substrate affinity and physiological efficiency at pH 3.5 than at pH 2. 5. The cod pepsins are glycoproteins, and their amino acid composition resembles that of porcine cathepsin D more than that of porcine pepsin. 6. The N-terminal sequence of Atlantic cod pepsins is substantially different from that of porcine pepsin. This indicates a significant evolutionary gap between fish and mammalian pepsins.
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PMID:Catalytic properties and chemical composition of pepsins from Atlantic cod (Gadus morhua). 211 46