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Incredible Enzymes

Incredible Enzymes. Mrs. Tuma SBI 4UI. Thermodynamics:. First Law of Thermodynamics: The total amount of energy in the universe is constant, although the energy may change form (e.g.: heat, light, kinetic energy). Thermodynamics:. Second Law of Thermodynamics:

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Incredible Enzymes

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  1. Incredible Enzymes Mrs. Tuma SBI 4UI

  2. Thermodynamics: • First Law of Thermodynamics: • The total amount of energy in the universe is constant, although the energy may change form (e.g.: heat, light, kinetic energy)

  3. Thermodynamics: • Second Law of Thermodynamics: • Disorder (entropy) in the universe is always increasing • Energy is transferred into less useable forms over time!

  4. The Paradox: • Biological systems “appear” organized, but entropy is always increasing • How does anything get done?

  5. Enter Enzymes! • What is an enzyme? • A biological protein catalyst which reduces the activation energy required for a reaction to occur • What is activation energy? • The amount of energy required to start a reaction • Most biological reactions would not happen spontaneously without a reduction in activation energy

  6. Energy and Biological Reactions:

  7. Check it out! • http://ed.ted.com/lessons/activation-energy-kickstarting-chemical-reactions-vance-kite

  8. The Theory: Lock and Key Theory: • One enzyme (the lock) has a specific shape for one set of substrates (the key) and is very rigid

  9. Is “Lock and Key” Theory the best fit?

  10. The Theory: • Induced-Fit Theory • Good evidence that shape of the active site changes somewhat after substrate(s) bind to it • Enzyme’s active site is still very specific to the substrate but it is not so rigid

  11. Controlling by Competitive Inhibition: • Competitive Inhibition: • A “look-alike” molecule binds to the active site • Enzyme unable to bind with substrate • Slows down or stops enzyme from acting since some enzymes are inactivated • Many common drugs and pesticides work this way!

  12. Competitive Inhibition

  13. Common Competitive Inhibitors: • Penicillin • kills susceptible bacteria by specifically inhibiting the enzyme that catalyzes the final step in cell wall biosynthesis • ACE Inhibitors • Inhibit enzyme that make angiotensin II hormone (it constricts blood vessels, narrowing them and increasing blood pressure) • Commonly used to treat high blood pressure

  14. More Interesting Competitive Inhibitors… • Ethanol • Given as an antidote in methanol poisoning as it competes for the same metabolizing enzyme but produces less toxic effects • Grapefruit!!! • Compound(s) in grapefruit juice inhibit a drug-metabolizing enzyme in the small intestine, allowing for increased levels of the drug in the body • Drugs can build up to toxic levels!

  15. Common Competitive Inhibitors • http://www.cbc.ca/news/health/story/2012/11/26/grapefruit-juice-drug-interactions.html

  16. Non-Competitive Inhibition • Molecules can bind to a site adjacent to the active site and change the shape of the active site • Substrate may then be unable to bind to the active site • Eg: Heavy Metals

  17. Allosteric Regulation • Molecules may bind to a site away from the active site and either increase enzyme action (allosteric activation) or decrease enzyme action (allosteric deactivation)

  18. Common Allosteric Regulators: • Many vitamins act as allosteric regulators co-enzyme: vitamin aiding an enzyme’s action co-factor: a mineral aiding an enzyme’s action

  19. The End!

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