Malate dehydrogenase curves

Use the plot of AiAQ vs. time to calculate AH/min over the linear portion of the curve. Convert the rate in absorbance terms to activity units. One enzyme unit is the amount of malate dehydrogenase that catalyzes the reduction of 1 micromole of oxaloacetate to L-malate in 1 minute under the described assay conditions. The reduction of 1 micromole of oxaloacetate leads to the oxidation of 1 micromole of NADH therefore, Equation E10.4 may be used to calculate the specific activity of malate dehydrogenase. 

Product inhibition is a cause of nonlinearity of reaction progress curves during fixed-time methods of enzyme assay. For example, oxaloacetate produced by the action of aspartate aminotransferase inhibits the enzyme, particularly the mitochondrial isoenzyme. The inhibitory product may be removed as it is formed by a coupled enzymatic reaction malate dehydrogenase converts the oxaloacetate to malate and at the same time oxidizes NADH to NADL... 

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