Membrane-bound DD-carboxypeptidases from Bacillus megaterium KM general properties, substrate specificity and sensitivity to penicillins, cephalosporins and peptide inhibitors of the activity at pH5.
1. The membrane from Bacillus megaterium KM contained a dd-carboxypeptidase with optimum activity under the following conditions: pH5.2, bivalent cation, 3mm; ionic strength, 40mm; temperature, 35 degrees C. It was inactivated by treatment with p-chloromercuribenzoate but was fairly insensitive to 2-mercaptoethanol. 2. The enzyme was inhibited by penicillins and cephalosporins. The inhibition of this enzyme was partially reversed on dialysis but 0.2m-2-mercaptoethanol could neither prevent nor reverse the inhibition. 3. The enzyme was extremely sensitive to changes in the configuration and size of the side chain of the C-terminal dipeptide of the substrate. An aliphatic side chain of a well-defined length and polarity was required in the residue that precedes the C-terminal dipeptide. 4. The enzyme was inhibited by a wide range of analogues of the peptidic portion of the natural substrate.
D001410:Bacillus megaterium / Q000201:enzymology*; D002250:Carbon Radioisotopes; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors; D002462:Cell Membrane / Q000201:enzymology; D002511:Cephalosporins / Q000494:pharmacology; D002729:Chloromercuribenzoates; D003902:Detergents; D004492:Edetic Acid; D004590:Electrophoresis, Paper; D006863:Hydrogen-Ion Concentration; D008274:Magnesium; D008623:Mercaptoethanol; D008854:Microscopy, Electron; D010405:Penicillinase; D010406:Penicillins / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D014316:Tritium
D002250:Carbon Radioisotopes; D002511:Cephalosporins; D002729:Chloromercuribenzoates; D003902:Detergents; D010406:Penicillins; D010455:Peptides; D014316:Tritium; D008623:Mercaptoethanol; D004492:Edetic Acid; D002268:Carboxypeptidases; D010405:Penicillinase; D008274:Magnesium