I. Enzymes: Special proteins

catalysts A. Function of enzymes: act as catalysts (which speed up chemical reactions) -Enzymes work by lowering activation energy. specific B. Enzymes are specific to the substrates on which they work.

C. Substrate—the reactant (substance) on which the enzyme works unchanged D. Enzymes remain completely unchanged by the reaction.

E. Factors affecting the rate at which an enzyme can work: 1. temperature 2. pH 3. concentration (of enzyme and of substrate)

Lock-and-Key Method F. Enzymes work through a method called the Lock-and-Key Method. substrates enzyme enzyme-substrate complex (with active site- where action takes place) product enzyme

Lock-and-Key

G. Enzymes’ names end in -ase.

Example: catalase It catalyzes the decomposition (break-down) of hydrogen peroxide into water and oxygen. 2H 2 O 2  2H 2 O + O 2 hydrogen peroxide  water + oxygen

Additional notes on catalase: One molecule of catalase can break down 40 million molecules of hydrogen peroxide each second. Hydrogen peroxide is a harmful byproduct of certain cellular processes in organisms. Catalase is an enzyme that breaks down hydrogen peroxide. Cells make catalase in order to convert the hydrogen peroxide into harmless substances. Reference for last two slides: (Found )

Example: carbonic anhydrase It is found in red blood cells where it catalyzes the reaction: CO 2 + H 2 O  H 2 CO 3 carbon dioxide + water  carbonic acid

Additional notes on the enzyme carbonic anhydrase: It enables red blood cells to transport carbon dioxide from the tissues to the lungs. One molecule of carbonic anhydrase can process one million molecules of CO 2 each second. Catalase/hydrogen peroxide reaction demo