Fumerase is an enzyme in the citric acid cycle that catalyzes the conversion of fumerate to L-malate. Given the fumerate (substrate) concentrations and initial velocities below, construct a Lineweaver-Burk plot and determine Vmax and Km values for the fumerase catalyzed reaction.



Fumerate (mM) Rate (mmol l-1 min-1)




2.0 2.5

3.3 3.1

5.0 3.6

10.0 4.2



b) Fumerase has a molecular weight of 194,000 and is composed of four identical subunits, each with an active site. If the enzyme concentration is 1 x 10-8 M for the experiment in part

(a), calculate kcat value for the reaction of fumerase with fumerate.

Note: units for kcat are reciprocal seconds (s-1).