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Proteins  Enzymes are specialized Proteins Catalysts  Act as Catalysts to accelerate a reaction  Not permanently  Not permanently changed in the process 2

catalyze  Are specific for what they will catalyze Reusable  Are Reusable ase  End in –ase-Sucrase-Lactase-Maltase 3

weakening bonds which lowers activation energy Enzymes work by weakening bonds which lowers activation energy 4

5 Free Energy Progress of the reaction Reactants Products Free energy of activation Without Enzyme With Enzyme

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substance enzyme substrate The substance (reactant) an enzyme acts on is the substrate 7 Enzyme Substrate Joins

restricted region enzyme binds substrate  A restricted region of an enzyme molecule which binds to the substrate. 8 Enzyme Substrate Active Site

shape  A change in the shape of an enzyme’s active site  Induced  Induced by the substrate 9

changeconfiguration enzyme’s active site  A change in the configuration of an enzyme’s active site (H+ and ionic bonds are involved).  Inducedsubstrate.  Induced by the substrate. 10 Enzyme Active Site substrate induced fit

 Three factors: 1.Environmental Conditions 2.Cofactors and Coenzymes 3.Enzyme Inhibitors 11

1. Extreme temperatures are the most dangerous 1. Extreme temperatures are the most dangerous - high temps denature (unfold) enzyme. - high temps may denature (unfold) the enzyme. 2.pH (most like pH near neutral) 3.Substrate concentration- increasing substrate increases enzyme activity until levels are the same. 12

 Inorganic substances (zinc, iron) vitamins enzymatic activity  Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes needed for proper enzymatic activity.  Example: Ironquaternary structure-hemoglobin pick up oxygen. Iron must be present in the quaternary structure - hemoglobin in order for it to pick up oxygen. 13

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. 14 Enzyme Competitive inhibitor Substrate

15 b. Noncompetitive inhibitors: do not enter the active sitebind to another part of theenzymeenzyme 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