An AP Biology Lab: Inhibiting the Action of Catechol Oxidase

Lab: Inhibiting the Action of Catechol Oxidase By: Kimberly G. Introduction: In this lab, Mr. Greene's sixth period AP Biology class split into groups "to investigate inhibition of enzyme activity by specific chemicals called inhibitors" (1). Group three pondered this lab's inhibitor, phenylthiourea (PTU). Is it a competitive inhibitor? That is an inhibitor that literally "competes" with the substrate by mimicking it, and thus "wins" the position at the active site of the enzyme. The blocked …

…competitive and noncompetitive inhibitors, Group Three deduced that PTU is, in fact, a noncompetitive inhibitor. So, Group Three's hypothesis was supported, and since there was no reaction after the substrate's concentration was raised, the prediction was confirmed, too. There are no errors that could have affected Group Three's results to be documented besides general lab procedure errors. References: 1. Giles Morgan, J. and Brown Carter, M.E. Investigating Biology 2nd ed. Menlo Park, CA: Benjanin/Cummings, 1996.