Enzymes

This chapter defines an enzyme as a catalyst which brings about a specific reaction by increasing the rate of reaction while remaining unchanged in the process. Also, the enzyme here cannot affect the equilibrium of a reaction. The chapter points out that an enzyme is a protein that binds substrates and lowers the activation energy of the reaction it catalyses, as the active site binding the substrate is perfectly complementary to the transition state. An enzyme aligns substrates and provides a catalytic site, which is a small region of the protein that contains chemical groupings essential for the catalysis. The chapter discusses enzyme kinetics. This explores enzymes by measuring reaction rates and the Michaelis-Menten equation which explains the kinetics of many enzyme-catalysed reactions in terms of the substrate binding to the enzyme and the enzyme-substrate complex breaking down to liberate products. An enzyme displaying Michaelis-Menten kinetics gives a hyperbolic curve. This happens when the initial reaction velocity is plotted against increasing substrate concentration.