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Dr. Robert Moore
Assistant Professor

 

September 15, 2012 publication

E.N. Ndontsa, R.L. Moore, D.C. Goodwin. “Stimulation of KatG catalase activity by peroxidatic electron donors” Archives of Biochemistry and Biophysics 525 (2012) 215–222.

Catalase-peroxidases are enzymes that can break down hydrogen peroxide via two different mechanisms but using a single active site that is overlayable with active sites from monofunctional peroxidases. There is evidence to support the belief that the enzyme chooses which mechanism to use based on the pH and available substrates. As I was finishing my time at Auburn University, I became curious as to if the enzyme “preferred” one mechanism over the other. I ran a test to observe the decrease in catalase activity when peroxidase substrates were present at a pH that fell between the optimum for the two mechanisms. The results were shocking as we observed higher catalase rates in the presence of a wide variety of peroxidase substrates than catalase rates when peroxidase substrates were unavailable. Since I have left Auburn, another graduate student picked up on my work using the form of the enzyme from the pathogen Mycobacterium tuberculosis. She repeated my experiments and found the catalase enhancement to be near 100-fold, making this enzyme (that looks like a peroxidase) a highly efficient catalase across a much broader range of pH than previously known. Considering that M. tuberculosis carries this enzyme in its periplasmic space, our bodies’ defense mechanism of blasting infecting bacteria with hydrogen peroxide is rendered nearly useless. This enzyme also exists in the periplasmic space of other highly pathogenic bacteria, such as those causing bubonic plague, E. coli food poisoning, and Legionnaires disease. I’m excited to report that this past spring my Ph.D. advisor and I worked to prepare a manuscript reporting our observations, and it has been accepted into the September 15 issue of Archives of Biochemistry and Biophysics. To view the abstract and more click here