Chapter 12, Problem 30CQ

(a)

Summary Introduction

To explain: The apparent K_M and V_max values in the presence and absence of inhibitor.

Concept introduction: Enzymes are biological protein catalysts which alter the speed of the reaction in the biological system. The chemical reactions which are catalyzed by these enzymes are studied under enzyme kinetics. The reaction rate is measure based on the rate at which the substrate of the enzymes combines with the enzyme and forms the products. K_M is the Michaelis-Menton constant. K_M value is not a direct measure of the affinity of the enzyme towards the substrate, but the concentration of S, where the velocity at maximum is half. V_max is the maximum velocity which the enzyme catalyses the reaction.

$\text{The rate of enzyme reaction }\left(\text{V}\right)\text{ =}\frac{{\text{V}}_{\text{max}}\left[\text{S}\right]}{\left({\text{K}}_{\text{M}}\text{+}\left[\text{S}\right]\right)}$. The Lineweaver-Burk plot can be used to find the K_M and V_max values. Enzyme inhibitors are those that block the enzyme activity.

(b)

Summary Introduction

To explain: The kind of inhibitor threo-sphingosine is for the enzyme sphingosine kinase.

Concept introduction: Enzymes are biological protein catalysts which alter the speed of the reaction in the biological system. Enzyme inhibitors are those that block the enzyme activity. The Lineweaver-Burk plot can be used to find the K_M and V_max values.