Proline iminopeptidase from Lactobacillus delbrueckii subsp. bulgaricus CNRZ 397: purification and characterization.
Proline iminopeptidase (PepIP) is a major peptidase in Lactobacillus delbrueckii subsp. bularicus CNRZ397, encoded by the pepIP gene. Amplification and expression of this gene in Escherichia coli K12 resulted in a very high level of enzyme production. Moreover, export into the E. coli periplasm of 45% of PepIP activity allowed us to purify the enzyme easily by a single ion-exchange chromatography step. PepIP is a trimer of Mr 100000 , composed of three identical subunits. In the presence of 0.1% BSA, PepIP activity was optimal at pH 6-7 and stable at temperatures below 40 degrees C. The enzyme was strongly inhibited by 3,4-dichloroisocoumarin, a serine protease inhibitor, by bestatin and by heavy metal ions. It was also inactivated by p-chloromercuribenzoate, but was reactivated by adding dithiothreitol. PepIP is characterized by a high specificity towards di- or tripeptides with proline at the NH2-terminal position, but is not able to hydrolyse longer peptides, or peptides with hydroxyproline at the NH2-end. The NH2-terminal amino acid sequence of the purified PepIP corresponds to the amino acid sequence deduced from the nucleotide sequence of the pepIP gene.
Centre de Génétique Moléculaire et Cellulaire, Université Claude Bernard-Lyon, France.
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Gilbert
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Atlan
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Blanc
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Portalier
D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005798:Genes, Bacterial; D007202:Indicators and Reagents; D007477:Ions; D007778:Lactobacillus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D013379:Substrate Specificity
D007202:Indicators and Reagents; D007477:Ions; D009842:Oligopeptides; D000626:Aminopeptidases; C022450:prolyl aminopeptidase