3 What Are Enzymes? Enzymes are Proteins that act as a Catalyst to accelerate a chemical reaction.
4Enzymes Enzymes are specific for certain substance. (They are made for a specific chemical) They are reusable! Their names end is –ase. Example: LactaseTheir names end is –ase. Example: Lactase
5 How do enzymes Work? Enzymes work by weakening bonds and lowering the activation energy of a reaction.
6Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme
7 Enzyme-Substrate Complex substance The substance or reactant chemical the enzyme works on is called the substrate. Enzyme Substrate Joins
8 Active Site The substrate bonds to the active site of the enzyme. Enzyme Substrate Active Site
9 Enzyme Activity Once the substrate bonds, the enzyme changes shape to induce the reaction
10 Enzyme Activity The substrate is chemically changed then released, and the enzyme returns to normal. It can now move on to a new substrate. Enzyme Active Site substrate induced fit
11 What Affects Enzyme Activity? Three factors:Three factors: 1.Environmental Conditions 2.Cofactors and Coenzymes 3.Enzyme Inhibitors
12 1. Environmental Conditions 1. Extreme temperatures can damage or denature enzymes 1. Extreme temperatures can damage or denature enzymes 2. 2.Strong changes in pH (in either direction) can also denature enzymes 3. 3.Too many ions (salts) can also denature enzymes.
13 2. Cofactors and Coenzymes Inorganic substances (zinc, iron) vitamins enzymatic activityInorganic substances (zinc, iron) and vitamins are sometimes needed for proper enzymatic activity. Example:Example: Ironquaternary structure-hemoglobin pick up oxygen. Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen. Without Iron, it doesn’t work.
14 Enzyme Inhibitors a. Inhibitors: a. Inhibitors: chemicals that pretend to be the enzyme’s substrate (but won’t react) or bond to the enzyme at a different point to “shut it off” keep enzymes from working until needed. Enzyme Competitive inhibitor Substrate