Illinois State Univeristy1, Chemistry, Normal, IL 61790 Truman College2, Biology, Chicago, IL 60640 Illinois State University3, Chemistry, Normal, IL 61790
Catalase is an enzyme critical for cellular reduction of hydrogen peroxide and other reactive oxygen species. We have isolated the gene encoding catalase from Listeria monocytogenes and expressed the recombinant 6x-His-tagged form in Escherichia coli. In vitro, the enzyme worked over a large range of temperatures and pH values. The Michaelis constant was similar from 5°C to 37°C. The isolated enzyme shows a multisubstrate characteristic, implying a similarity to mammalian catalase. It also appears to be active until the pKa of 11.65, the value for hydrogen peroxide. The pKa values points to Histidine and Lysine/Arginine sidechains in the active sites.