How do drugs inhibit enzyme catalysed reactions?
• Pharmaceutical industry, rational drug design through understanding enzyme mechanisms. • for the Oreo lyase experiment, the chocolate chip cookie decreased the rate of reaction with the correct substrate because it looks like an ooreo but cannot undergo the lyase (splitting) reaction. There are three types of inhibition: • Competitive. Competition between S and I for binding to enzyme decreases rate of reaction, v. Overcome by increasing [S] which means that the parameter Km is increased. The effect of a chocolate chip or or Fig Newtons on oreo lyase! Diagnostically, a decrease in Km and no change in Vm. • Non-competitive. The inhibitor binds both to free E and to ES complex and decreases the rate of the reaction, v. Not overcome by increasing [S] which means that the parameter Vm is decreased. Diagnostically, a decrease in Vm and no change in Km. • Irreversible: poisons like nerve gas that inhibits acetylcholine esterase.
