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Enzymes

Enzymes. What Are Enzymes?. Most enzymes are Proteins ( tertiary and quaternary structures) Act as Catalyst to accelerate a reaction Create a new reaction pathway “a short cut” Not permanently changed in the process. Enzymes. Are specific for what they will catalyze Are Reusable

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Enzymes

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  1. Enzymes

  2. What Are Enzymes? • Most enzymes are Proteins (tertiary and quaternary structures) • Act as Catalyst to accelerate a reaction • Create a new reaction pathway “a short cut” • Not permanently changed in the process

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

  4. How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy

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

  6. Enzyme Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Enzymes are specific to their substrate Joins Substrate

  7. Enzyme Active Site • A restricted regionof an enzyme molecule which binds to the substrate. Active Site Substrate

  8. The Lock and Key Hypothesis • Fit between the substrate and the active site of the enzyme is exact • Like a keyfitsinto a lockveryprecisely • The key is analogous to the substrateand the enzyme is analogous to the lock. • Temporary structure called the enzyme-substratecomplexformed • Products have a differentshapefrom the substrate • Once formed, they are releasedfrom the active site • Leavingit free to becomeattached to anothersubstrate

  9. S E E E Enzyme may be used again Enzyme-substrate complex P P Reaction coordinate The Lock and Key Hypothesis

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

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

  12. 1. Environmental Conditions 1. Extreme Temperature are the most dangerous - high tempsmay denature (unfold) the enzyme. 2. pH (most like 6 - 8 pH near neutral) 3. Ionic concentration (salt ions)

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

  14. Enzyme Competitive inhibitor Two examples of Enzyme Inhibitors Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrateand compete with it for the active site. Substrate

  15. Noncompetitive Inhibitor Enzyme active site altered The effect of enzyme inhibition Noncompetitive inhibitors: Inhibitors that do not enter theactive site, but bind toanother partof the enzymecausing the enzyme to change its shape, which in turn alters the active site. Substrate

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