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Enzymes

Enzymes. Enzymes. The Need for Enzymes. Many important exergonic rxns require more E A than cells can provide Other rxns require specific collision angles, slowing rxn rate. Lowering E A. Enzymes lower E A to a level that’s safe and attainable. Catalysis.

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Enzymes

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  1. Enzymes Enzymes

  2. The Need for Enzymes • Many important exergonic rxns require more EA than cells can provide • Other rxns require specific collision angles, slowing rxn rate

  3. Lowering EA • Enzymes lower EA to a level that’s safe and attainable

  4. Catalysis • Enzyme binds substrate(s) at active site • Enzyme changes shape to separate or combine molecules • Enzyme reverts to original shape

  5. Specificity • Enzymes are substrate specific • 3-D shape makes enzymes specialized • An enzyme binds substrate(s) at active site Active Site

  6. Rate of Rxns • As [substrate] ↑, Rate ↑ Enzyme Saturation Rate [substrate]

  7. Rate of Rxns Optimal Range • Temperature • As temp ↑, collisions are more frequent (rate ↑) • At high temps, h-bonds break, changing enzyme shape (rate ↓) Rate Denaturation Temperature

  8. Rate of Rxns

  9. Rate of Rxns

  10. Enzyme Regulation • Molecules bind to enzymes to alter their functions • Activation • Cofactors • Nonprotein helpers • Coenzymes • Organic cofactors • Cooperativity • Substrate = Activator

  11. Enzyme Regulation • Inhibition • Competitive • Blocks active site • Noncompetitive • Changes enzyme shape Active Site Allosteric Site

  12. Enzyme Regulation • Feedback Inhibition • Product inhibits enzyme

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