This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Szwajcer-Dey, E Articles by Breddam, K Search for Related Content PubMed PubMed Citation Articles by Szwajcer-Dey, E Articles by Breddam, K

 Previous Article  |  Next Article 

J Bacteriol. 1992 April; 174(8): 2454-2459

research-article

Proline-specific endopeptidases from microbial sources: isolation of an enzyme from a Xanthomonas sp.

Carlsberg Research Laboratory, Valby, Denmark.

ABSTRACT

An extensive screening among microorganisms for the presence of post-proline-specific endopeptidase activity was performed. This activity was found among ordinary bacteria from soil samples but not among fungi and actinomycetes. This result is in contrast to the previous notion that this activity is confined to the genus Flavobacterium. A proline endopeptidase was isolated from a Xanthomonas sp. and characterized with respect to physicochemical and enzymatic properties. The enzyme is composed of a single peptide chain with a molecular weight of 75,000. The isoelectric point is 6.2. It is inhibited by diisopropylfluorophosphate and may therefore be classified as a serine endopeptidase. The activity profile is bell shaped with an optimum at pH 7.5. By using synthetic peptide substrates and intramolecular fluorescence quenching it was possible to study the influence of substrate structure on the rate of hydrolysis. The enzyme specifically hydrolyzed Pro-X peptide bonds. With Glu at position X, low rates of hydrolysis were observed; otherwise the enzyme exhibited little preference for particular amino acid residues at position X. A similar substrate preference was observed with respect to the amino acid residue preceding the prolyl residue in the substrate. The enzyme required a minimum of two amino acid residues toward the N terminus from the scissile bond, but further elongation of the peptide chain by up to six amino acid residues caused only a threefold increase in the rate of hydrolysis. Attempts to cleave at the prolyl residues in oxidized RNase failed, indicating that the enzyme does not hydrolyze long peptides, a peculiar property it shares with other proline-specific endopeptidases.

This article has been cited by other articles:

• Harris, M. N., Madura, J. D., Ming, L.-J., Harwood, V. J. (2001). Kinetic and Mechanistic Studies of Prolyl Oligopeptidase from the Hyperthermophile Pyrococcus furiosus. J. Biol. Chem. 276: 19310-19317 [Abstract] [Full Text]