Plot these inverted values to make a Lineweaver-Burk plot. First one might repeat the process in B above to determine whether each compound functions as a substrate or not. Observations of colored products might indicate that 540 nm is not a reasonable choice for further measurement. The compound is a substrate. You should vary the concentration of the compound used in the reaction mixture.
Serial dilutions come to mind.
Absorbance should be measured as before at 30-sec intervals after adding the homogenate and thorough mixing . On your own time , determine the K m and V max for this enzyme-substrate combination, and compare them to those with catechol from part C above. The compound is not a substrate. The structure of the compound may be similar enough to the substrate, catechol, to bind at the active site, but may structurally different enough to avoid producing colored products. If this model holds, then the analog may compete with catechol for the active site on the enzyme.