following data are obtained for an enzyme-catalyzed reaction in the presence and absence of inhibitor A V(mmol ml min) [S](mM) Without A With A 0.2 5.0 3.0 0.4 7.5 5.0 0.8 10.0 7.5 1.0 10.7 8.3 2.0 12.5 10.7 4.0 13.6 12.5 1, Using double-reciprocal plots of the data, determine the type of inhibition that has occurred. 2. Does inhibitor A combine with E, with ES or with both? Explain. Solution 1. The double-reciprocal plots intersect on the y-axis, so the inhibition is competitive. 2. The inhibitor combined only with E, the free enzyme. A competitive inhibitor cannot combine with ES because inhibitor and the substrate compete for the same binding site on the enzyme.