Enzymes: Biological Catalysts  Special group of biomolecules, usually proteins.  Help make chemical reactions happen … rxns necessary for life functions!  “Biological catalysts” - speed up rates of reactions  Function based on shape.  Shape based on chemical composition & environmental conditions.

Enzyme Reactions Metabolism: Complete set of chemical rxns in a body. Enzymes catalyze these rxns. Divided into 2 types of rxns: a. Catabolic: Lg. Complex molecules broken down to simpler ones & release energy. b. Anabolic: Building larger molecules fr. Smaller ones (energy input)

Example of Enzyme Reactions Lactase: Breaks down lactose (milk sugars) Pepsin: Breaks down proteins DNA Polymerase: Adds nucleic acid bases to growing DNA strands during DNA replication. Kinase: attaches phosphate groups; ATP production

Enzymes speed reactions up!  Chemical Rxns require reactants collide/contact Reactants ----> Products  Enzymes make it easier for reactions to occur by putting stress on specific bonds or atoms w/in molecules.  Lower ACTIVATION ENERGY needed for rxns. To procede (These rxns would occur anyway, slower rate)

Enzymes lower activation energy ACTIVATION ENERGY = Energy needed to “jump start” rxn (energy required for rxn to proceed)

Enzyme-Substrate Complex Substrate = Reactant molecules; fit into enzymes. ACTIVE SITE: Location where substrate binds. Enzyme will only bind to specific substrates based on SHAPE! (Lock & Key fit)

Enzymes in Action a.Reactantc. enzyme b.Active sited. products

Enzyme shape is important to fxn Enzyme fxn depends on shape of active site. Shape of enzyme can be affected by …  Temperature?  pH?  Presence of other binding molecules (inhibitors or “helpers”)

Denaturation: Enzymes Unravel and Stop Functioning Enzyme shape can be affected by:  Temperature  pH By interfering with bonds, changes in temp. and pH can change enzyme shape. Substrate does fit in active site.

Lab: Part 1 Objectives: 1. Observe reaction catalyzed by CATALASE. H 2 O > H 2 O + O 2 Hydrogen Peroxide wateroxygen 2. Determine if enzymes are reusable or are they changed by the reactions they catalyze.

Lab: Part 2 Objectives: 1. Determine the optimal temperature and pH conditions of catalase. H 2 O > H 2 O + O 2 Hydrogen Peroxide wateroxygen 2. Identify conditions that cause denaturation and explain how denaturation influences enzyme activity.

Optimal Catalase Activity

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