1 Chapter 20 Enzymes and Vitamins 20.1 Enzymes Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Enzymes are Biological Catalysts Enzymes are proteins that  Catalyze nearly all the chemical reactions taking place in the cells of the body.  Increase the rate of reaction by lowering the energy of activation. Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 Names of Enzymes The name of an enzyme  Usually ends in –ase.  Identifies the reacting substance. For example, sucrase catalyzes the reaction of sucrose.  Describes the function of the enzyme. For example, oxidases catalyze oxidation.  Can be a common name, particularly for the digestive enzymes such as pepsin and trypsin.

4 Enzymes are classified by the reaction they catalyze. ClassType of Reactions catalyzed OxidoreductasesOxidation-reduction TransferasesTransfer groups of atoms Hydrolases Hydrolysis LyasesAdd atoms/remove atoms to or from a double bond IsomerasesRearrange atoms LigasesUse ATP to combine small molecules Classification of Enzymes

5 Oxidoreductases and Transferases Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

6 Hydrolases and Lyases Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

7 Isomerases and Ligases Copyright © 2007 by Pearson Education, Inc. Publishing as Benjamin Cummings

8 Match the type of reaction with an enzyme 1) aminase2) dehydrogenase 3) isomerase4) synthetase A. Converts a cis-fatty acid to a trans-fatty acid. B. Removes 2 H atoms to form double bond. C. Combines two molecules to make a new compound. D.Adds NH 3. Learning Check

9 Match the type of reaction with an enzyme 1) aminase2) dehydrogenase 3) isomerase4) synthetase A. 3 Converts a cis-fatty acid to a trans-fatty acid. B. 2 Removes 2 H atoms to form double bond. C. 4 Combines two molecules to make a new compound. D. 1 Adds NH 3. Solution