8 research outputs found
Purification and Characterization of L,(L/D)-aminopeptidase from Guinea Pig Serum
Mammalian sera contain enzymes that catalyze the hydrolytic degradation
of peptidoglycans and molecules of related structure and are relevant for the metabolism
of peptidoglycans. We now report on a novel L,(L/D)-aminopeptidase found
in human and mammalian sera. The enzyme hydrolyses the pentapeptide L-Ala-Diso-
Gln-meso-DAP(vNH2)-D-Ala-D-Ala yielding the free L-alanine and the respective
tetrapeptide (KM 18 mM). L,(L/D)-aminopeptidase from guinea pig serum was highly
purified in four chromatographic steps, up to 700-fold. Molecular weight of the enzyme
was estimated by HPLC to be approximately 175,000. The configuration of alanine
obtained by hydrolysis of the pentapeptide was determined by oxidation with
L-amino acid oxidase. The amino acids sequence in the respective tetrapeptide was
deduced from the results of mass spectrometry. The novel L,(L/D)-aminopeptidase
also hydrolyzed alanine-4-nitroanilide (KM \ubc 0.6mM) and several peptides
comprising L-amino acids. Peptides containing D-amino acid at the amino end and
L-Asp-L-Asp were not the substrates for this enzyme. The purified enzyme
also exhibited enkephalin degrading activity, hydrolyzing enkephalins comprising L,L- and L,D-peptide bonds. The enzyme was inhibited strongly by metal chelating
agents, bestatin and amastatin