Enzyme Inhibition Examples Inhibitors Molecules that reduce the

Enzyme Inhibition Examples

Inhibitors Molecules that reduce the rate of enzymatic reactions Usually specific and work at low concentrations Block the enzyme but they do not usually destroy it Many drugs and poisons are inhibitors of enzymes in the nervous system.

Types of Enzyme Inhibition 1. Competitive Inhibition Compete with the substrate molecules for the active site The inhibitor’s action is proportional to its concentration Resembles the substrate’s structure closely 2. Noncompetitive Inhibition Not influenced by the concentration of the substrate Inhibits by binding irreversibly to the enzyme but not at the active site Cyanide

Types of Enzyme Inhibition Competitive Inhibition Non Competitive Inhibition

Penicillin Non Competative Interferes with the synthesis of cell walls of reproducing bacteria Inhibits an enzyme—transpeptidase Defective walls cause bacterial cells to burst and die Human cells are not affected because wehave cell membranes, not cell walls. Some people (perhaps 5% of the population) are allergic to penicillin

Aspirin Non Competitive Inhibition Inhibit the activity of the enzyme called cyclooxygenase (COX) Suppress the production of prostaglandins Cuts down on the pain signal to brain, swelling, and inflammation Ibuprofen and naproxen work this same way

Methotrexate Competitive inhibition Inhibits DNA synthesis in malignant tumor formation

CO Competitive inhibitor to oxygen when it comes to binding to the heme group of hemoglobin

Cyanide Non competitive Causes death by halting ATP production Binds to the allosteric site of the enzyme cytochrome oxidase Changes the shape of the active site so that the enzyme cannot pass electrons on and stops ATP production

Sarin Gas Competitive Nerve agent; interferes with the normal signaling between nerve cells Inhibiting the enzyme acetylcholinesterase If this neurotransmitter is not removed, the muscles don't relax. Binds at the active site on the cholinesterase molecule, making it unable to bind to acetylcholine.

Competitive vs. Non Completive Inhibition