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International Journal of Microbiology
Volume 2010, Article ID 196363, 7 pages
Research Article

Characterization of the Escherichia coli Antifungal Protein PPEBL21

1National Institute for Health, Rockville Pike, Bethesda, MD 20892, USA
2Department of Biotechnology, Kurukshetra University, Kurukshetra 136119, India
3Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007, India
4Research Institute of the McGill University Health Centre, Montrรฉal, QC, Canada H3G 1A4

Received 22 December 2009; Accepted 9 March 2010

Academic Editor: Marco Gobbetti

Copyright © 2010 V. Yadav et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An antifungal protein isolated from Escherichia coli BL21 (PPEBL21) and predicted to be alcohol dehydrogenase (ADH) was subjected to biological characterization. The PPEBL21, indeed, demonstrated propionaldehyde-specific ADH activity. The Km and Vmax of PPEBL21 were found to be 644.8 ๐œ‡ M and 1.2 U/mg, respectively. In-gel activity assay also showed that PPEBL21 was a propionaldehyde-specific ADH. The pI of PPEBL21 was observed to be 7.8. PPEBL21 was found to be stable up to a temperature of 4 0 โˆ˜ C with optimum activity at pH 7.5. The decrease in pH decreased the activity of PPEBL21. These results suggested that PPEBL21 having alcohol dehydrogenase activity and stability at significantly high temperature might be an important lead antifungal molecule. Experiments were performed to identify the possible target of PPEBL21 in the pathogen A. fumigatus. Results revealed that PPEBL21 inhibited completely the expression of a 16 kDa protein in A. fumigatus. The 16 kDa protein of A. fumigatus targeted by PPEBL21 was identified as a hypothetical protein by peptide mass fingerprinting. It is thus hypothesized that a 16 kDa factor is essentially required by A. fumigatus for survival and its impaired synthesis due to treatment with PPEBL21 may lead to the death of pathogen.