1. Enzymes Functions and Control

2. Enzyme Terms  Substrate - the material and enzyme works on.  Enzyme names: Ex. Sucrase - ase name of an enzyme - ase name of an enzyme 1st part tells what the substrate is. (Sucrose) 1st part tells what the substrate is. (Sucrose)

3. Enzyme Name  Some older known enzymes don't fit this naming pattern.  Examples: pepsin, trypsin  BUT…enzymes are proteins (-in = protein)

4. Active Site  The area of an enzyme that binds to the substrate.  Structure is designed to fit the molecular shape of the substrate.  Therefore, each enzyme is substrate specific.

6. Models of How Enzymes Work 1. Lock and Key model 2. Induced Fit model

7. Lock and Key Model  Substrate (key) fits to the active site (lock) which provides a microenvironment for the specific reaction.

8. Induced Fit Model  Substrate “almost” fits into the active site, causing a strain on the chemical bonds, allowing the reaction to proceed.

9. Substrate Active Site

10. Factors that Affect Enzymes  Environment  Cofactors  Coenzymes  Inhibitors  Allosteric Sites

11. Environment  Factors that change protein structure (denature) will affect an enzyme.  Examples:  pH shifts  temperature  salt concentrations

13. Cofactors  Non-protein helpers for catalytic activity.  Examples:  Iron  Zinc  Copper

14. Coenzymes  Organic molecules that affect catalytic activity.  Examples:  vitamins

15. Enzyme Inhibitors  Competitive - mimic the substrate and bind to the active site.  Noncompetitive - bind to some other part of the enzyme.

17. Allosteric Regulation  Cell’s can’t have enzymes turned on all the time  The control of an enzyme complex by the binding of a regulatory molecule.  Regulatory molecule may stimulate or inhibit the enzyme complex by causing it to change shape.  Works like a reversible non-competitive inhibitor

18. Allosteric Regulation

19. Feedback Inhibition  The end product of a metabolic pathway affects the function of an enzyme  A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway  Usually allosteric regulation