Why do we need Enzymes? Speed up rate of chemical reaction by lowering the activation energy (energy needed to start chemical reaction) Without enzyme Reactants With enzyme Activation energy without enzyme Activation Energy with enzyme Products
How do ENZYMES work? 1.The enzyme attaches to reactants 2.The reactants that bind to the enzyme are known as the substrates. 3.The part of the enzyme where the substrate attaches to the enzyme is called the active site. 4.The shape of the active site only fits the shape of the substrate, like a lock fits a key. Only the correct substrate binds to the enzyme.
Reactants/ Substrates Enzyme Lock-and-Key Mechanism- Enzymes can only bind to certain substrates
How do you speed up enzymes? 1.Add more of the enzyme. 2.Warm up the enzyme! Don’t warm it too much or something may happen
Once the enzyme and substrate are together, the enzyme holds the substrate so the reaction can occur. Once the reaction is over, the enzyme unlocks the product and the enzyme can start a new reaction with an identical substrate. Enzymes are not permanently changed or used up in reactions
A change in the pH of the enzyme can cause a change in the shape of the active site, therefore changing the activity of the enzyme.
17 What Affects Enzyme Activity? Three factors:Three factors: 1.Environmental Conditions 2.Cofactors and Coenzymes 3.Enzyme Inhibitors
18 1. Environmental Conditions 1. Extreme Temperature are the most dangerous 1. Extreme Temperature are the most dangerous - high temps denature (unfold) enzyme. - high temps may denature (unfold) the enzyme....Let's see......Let's see... 2.pH (most like 6 - 8 pH near neutral) 3.Ionic concentration (salt ions)
19 2. Cofactors and Coenzymes Inorganic substances (zinc, iron) vitamins enzymatic activity Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes need for proper enzymatic activity. –Example: Ironhemoglobin (a protein in red blood cells) pick up oxygen. Iron must be present in the hemoglobin (a protein in red blood cells) in order for it to pick up oxygen. Non-protein enzyme helpers (inorganic) organic cofactors
20 Two examples of Enzyme Inhibitors a. Competitive inhibitors: resemble enzyme’s normal substrate competeactive site a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Competitive inhibitor Substrate
21 Inhibitors b.Noncompetitive inhibitors: do not enter the active sitebind to another part enzymeenzyme change its shape alters the active site Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme active site altered Noncompetitive Inhibitor Substrate