Question

3. Congratulations! You have just secured a great job in a pharmaceutical company. You are doing an experiment in which you are measuring the rate at which succinic acid is converted to fumaric acid by an enzyme succinic dehydrogenase because you want to design a drug that can block this step in the metabolic pathway of a pathogenic bacteria. You decide to add a little malonic acid to make things interesting.. You observe that the reaction rate slows markedly and being a very smart graduate of Medgar Evers College, you conclude that malonic acid must be acting as an inhibitor. Design an experiment that will help you decide if malonic acid is acting as a competitive inhibitor or a noncompetitive inhibitor. Go to work and expect a promotion. Good luck.

Answer 1

An experiment can be designed where we first study the V max and Km of the reaction without the use of an inhibitor. Only the substrate and the enzyme are present in the reaction. After that we also perform an experiment  in the presence of the inhibitor and we study the Vmax and the Km constant.

If it is a competitive inhibitor, the rate of reaction can ultimately reach near to the Vmax. But the Km constant will be higher in the presence of an competitive inhibitor.

If it is a Non-competitive inhibitor, the rate of reaction does not reach its maximum as in the case of the absence of the inhibitor. BUt the Km constant remains same.

So by performing an experiment with and without the inhibitor, the type inhibition brought can be understood.