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Enzymes

Enzymes. Characteristics of Enzymes. Proteins Catalysts Speed up chemical reactions without being used up. Structure. An enzyme’s shape is very specific. If changed, we call it… DENATURED Can no longer catalyze reactions What kinds of things do you think could denature a protein?.

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Enzymes

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  1. Enzymes

  2. Characteristics of Enzymes • Proteins • Catalysts • Speed up chemical reactions without being used up

  3. Structure • An enzyme’s shape is very specific. • If changed, we call it… DENATURED • Can no longer catalyze reactions • What kinds of things do you think could denature a protein?

  4. Denaturation • Disruption of protein structure by • Heat: Break apart H bonds and disrupt hydrophobic attractions • Acids/ bases: Break H bonds between polar R groups and ionic bonds • Heavy metal ions: React with S-S bonds to form solids • Agitation: Stretches chains until bonds break

  5. Applications of Denaturation • Hard boiling an egg • Wiping skin with alcohol swab for injection • Cooking food to destroy E. coli

  6. How do enzymes work? • Lower Activation Energy to speed up rates of reaction • Reactions require energy to begin…enzymes lower the amount of energy required.

  7. Naming • Often end in “–ase” • Prefix refers to what substance it causes to react • Examples: maltase, sucrase, protease, carboxypeptidase

  8. Catalyzing Process • Unique 3-D shape determines which chemical reaction it catalyzes • Important Vocab: • SUBSTRATE: A specific reactant that an enzyme acts on.

  9. Important Vocab (cont.): • ACTIVE SITE: the region of the enzyme where the substrate will bind

  10. The enzyme and substrate bond to form the enzyme-substrate complex substrate Active site enzyme Enzyme-substrate complex

  11. Lock and Key Model + + E + S ES complex E + P P S S P

  12. Enzymes are very specific!

  13. TEMPERATURE • An enzyme’s optimal temperature = highest rate of reaction • Most human enzymes work best at 35-40 ºC. Optimum temperature Reaction Rate Low High Temperature

  14. WATCH OUT!!! If the temperature gets too high, the enzyme may be denatured!

  15. pH (Acid/Base) • The enzymes in your stomach will not work in your blood. • Most of your enzymes work best around a neutral pH

  16. Rate of Reaction • enzyme lab…

  17. Substrate Concentration Increasing substrate concentration increases the rate of reaction up to a certain point. • Limited by enzyme concentration, why? • Maximum activity reached when all of enzyme combines with substrate

  18. Substrate Concentration (cont.) Maximum activity Reaction Rate substrate concentration

  19. Enzyme Inhibition • Inhibitors: cause a loss of catalytic activity • May be competitive or noncompetitive

  20. Competitive Inhibition • Acompetitive inhibitor • Has a structure similar to substrate • Occupies active site • “Competes” with substrate for active site • Effects can be reversed by increasing substrate concentration

  21. Competitive Inhibition Image

  22. Noncompetitive Inhibition • A noncompetitive inhibitor • Binds to the enzyme (not at active site) & changes the shapeof enzyme & active site • Substrate cannot fit altered active site • Effect is not reversed by adding substrate

  23. Noncompetitive Inhibition Image

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