How enzyme function

Chemical reaction The cells carries out many chemical reactions. A + B C +D reactants products All the reactions that occur in a cell have an enzyme.

Enzymatic action Enzymes are organic catalysts that speed metabolic reactions. Most of the enzymes are proteins. The reactants in an enzymatic chemical reaction are called substrates. E + S ES E + P

Enzymes can be used over and over again. Enzymes have specific shape accommodating the shapes of their substrate. Enzymes can be used over and over again. Active site

Catalase Catalase speeds the breakdown of hydrogen peroxide to water and oxygen 2H2O2 2H2O + O2 catalase

Factors affecting enzyme activity Temperature Concentration (of enzyme or substrate) pH

Temperature Cold (ice bath)— slow chemical reaction Warm— speed chemical reaction Hot (boiling water bath)— enzyme denature

Concentration (of enzyme or substrate) Low—slower chemical reaction High— faster chemical reaction

pH pH<7 acidic pH=7 neutral pH>7 alkline Each enzyme— optimum pH speed the reaction best Low / high—affects hydrogen bonding and the structure of enzyme, reduced activity

Summary Factors Promote Enzyme Activity Inhibit Enzyme Activity Temperature Concentration pH

Experiments 1. Catalase Activity: what does the height of the bubble column mean? what’s the function of catalase? page 59 2. Effect of Temperature: finish table 5.2 page 60 3. Effect of Enzyme Concentration: finish table 5.3 page 61 4. Effect of pH on Enzyme Activity: finish table 5.4 page 62 11