Enzymatic Activity Analysis and Catalytic Essential Residues Identification of Brucella abortus Malate Dehydrogenase

Figure 7

Enzymatic activity of the MDH mutant forms. The activities of the six mutant forms of the MDH were detected by measuring absorbance at 340 nm for the reduction of OAA at 1 min intervals for 5 min at 40°C. The results showed that the substitutions of amino acids Arg 89, Asp 149, Arg 152, His 176, and Thr 231 almost abolished the activity of MDH. However, the mutant form with the substitutions of amino acids Asp178 kept 60% activities of the original MDH. The experiments were performed in triplicate.