Article Abstract:
The cloning, expression and inactivation of a peptidase gene expressing L-proline-beta-naphthylamide-hydrolyzing activity in Lactobacillus rhamnosus are reported. One complete open reading frame 903 nucleotides long was found in the SacI fragment, with another open reading frame following pepR, which was 459 bp long, found by additional sequencing. Results revealed that the cloned PepR of L. rhamnosus hydrolyzes Leu-Gly-Gly. Its substrate specificity is also different from that of L. helveticus PepR, as indicated by its ability to hydrolyze Pro-BetaNA, Phe-BetaNA and Leu-BetaNA.
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Article Abstract:
A prolinase (pepR) gene from an industrial Lactobacillus helveticus strain (53/7) was cloned, DNA sequenced and mRNA analyzed to examine the gene expression, regulation and interactions of these peptidolytic enzymes. Two ORFs, ORF1 and ORF2 were found. ORF2 had a promoter region overlapping that of ORF1. ORF1 coded a 35 kDa protein in Escherichia coli that was able to hydrolize dipeptides, with highest activity against Pro-Leu. ORF2 specified a 59.6 kDa protein that had significant homology to several members of the family of ABC transporters.
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Article Abstract:
Research was conducted to compare the identification of Lactobacillus casei and L rhamnosus strains by the API 50 CHL test and by species-specific PCR and to compare pulsed-field gel electrophoresis, randomly amplified polymorphic DNA analysis and ribotyping methods for the discrimination of closely related L casei and L rhamnosus strains. Results illustrate that species-specific PCR, due to rapid and easy performance, is a very useful tool for identifying species of the L casei group.
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