Purification and properties of a periplasmic aminoendopeptidase from Escherichia coli.
A periplasmic aminoendopeptidase from Escherichia coli has been purified to hemogeneity. It is a monomer of molecular weight 45000 and containing one -- SH group that is necessary for catalytic activity. The study of its substrate specificity indicated that the enzyme has both aminopeptidase and endopeptidase activity. The pH optimum for L-alanine p-nitroanilide hydrolysis is between 7 and 7.5 and that for 125I-labeled casein proteolysis between 7.3 and 7.6. The activation energy for the hydrolysis of L-anine p-nitroanilide was calculated to be 5.3 kcal X mol-1 (22.2 kJ X mol-1).
D000596:Amino Acids / Q000032:analysis; D000626:Aminopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D002151:Calorimetry; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000032:analysis; D013696:Temperature; D013816:Thermodynamics
D000596:Amino Acids; D013438:Sulfhydryl Compounds; D000626:Aminopeptidases