Article Abstract:
The X-prolyl dipeptidyl aminopeptidase (pepX) gene of Lactobacillus helveticus contains an open reading frame (ORF), a transcription initiation site, a promoter site and an inverted repeat structure. The PepX protein encoded by the ORF is structurally similar to the PepX proteins of Lactococcus lactis and Lactobacillus delbrueckii. The protein is a dimer containing sulfhydral groups near the active site. PepX activity is inhibited by heavy metal ions but is unaffected by EDTA. Escherichia coli expressing the pepX gene produces active PepX.
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Article Abstract:
Lactobacillus helveticus also has an iminopeptidase, aside from the prolinase, which it generates by cloning its gene with the aid of a L. helveticus proline iminopeptidase gene (pepI). PepI and two genes coding for putative members of the ABC transporter family of proteins were found to be organized in an operon-like structure of three open reading frames. Overproduction, purification and enzymic characterization of the recombinant L. helveticus pepI are also described.
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Article Abstract:
A study was conducted on the cloning and characterization of two genes, pepQ and orfZ, encoding a prolidase and a prolidase-like protein from Lactobacillus delbrueckii subsp bulgaricus. The findings show that orfZ is a cryptic gene expressed at a very low level under the growth conditions employed. Moreover, homologues of the Lb debrueckii subsp bulgaricus orfZ and pepQ genes seem to be present in both Lb delbrueckii subsp lactis and Lactobacillus helveticus.
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