Enzymes AP Biology

General Information Globular proteins Unique 3 dimensional shape Active site: pocket or groove where substrate binds

General Information Catalysts Speed up chemical reactions Lower activation energy Not used up in chemical reaction

General Information Substrate specific Enzyme substrate pairs Catalase – hydrogen peroxide Sucrase – sucrose

Action – Induced Fit Model Substrate binds to enzyme at active site Interaction between substrate and active site

Action – Induced Fit Model Bonds in substrate stressed Bonds break Products released

Action – Induced Fit Model Substrate binds to enzyme at active site Interaction between substrate and active site Bonds form between reactants

Temperature & Rate Increasing temperature increases rate Increase temperature increases speed of molecules Increase speed of molecules increases number of collisions

Temperature & Rate Optimal temperature Temperature that produces max. rate.

Temperature & Rate Temperature above optimal Enzyme denatured (changes shape) Reaction drops then stops

pH & Rate Optimal pH pH with at max. rate

pH & Rate Above optimal – rate decreases Lower [H+] interferes with enzyme shape

pH & Rate Below optimal – rate decreases Higher [H+] interferes with enzyme shape

pH & Rate Extreme changes – rate zero Enzyme denatures

Control of Chemical Reactions Inhibitors – Competitive Inhibitor competes with substrate for active site

Control of Chemical Reactions Inhibitors – Noncompetitive Inhibitor binds to site other than active site

Control of Chemical Reactions Allosteric Enzymes Two conformations – active & inactive Activator stabilizes active form Inhibitor stabilizes inactive form