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Enzymes

Enzymes . What are they?. Organic/Biological Catalysts Proteins Reusable There’s over 40,000 found in humans Usually end in the suffix – ase Named after what it “eats” (ex: if an enzyme is meant to eat lact ose the enzyme is lact ase ). How do they work?.

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Enzymes

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  1. Enzymes

  2. What are they? • Organic/Biological Catalysts • Proteins • Reusable • There’s over 40,000 found in humans • Usually end in the suffix –ase • Named after what it “eats” (ex: if an enzyme is meant to eat lactose the enzyme is lactase)

  3. How do they work? • Enzymes possess an active site (which is like a cleft in the molecule) • The active site is where its food (substrate) goes into • When the substrate binds to the enzyme it is called an enzyme substrate complex • A new substrate will then be synthesized (created) or the old one will be split • Enzymes DO NOT change in the process

  4. Reactions • Enzymes CANNOT create reactions they only speed them up • Enzymes speed up reactions by lowering the activation energy (energy needed to get the reaction to take place) • There are two parts to a chemical reaction: reactants (what goes in) and products (what comes out) • Example: Carbonic anhydrase is an enzyme found in RBCs where it catalyzes the reaction CO2 + H2O ↔ H+ + HCO3− this allows blood to transport CO2 from the tissues to the lungs (one molecule of this enzyme can process one million molecules of CO2 each second

  5. Synthesis Reaction Active site

  6. Enzymes Specific Properties Increase rate of the reaction Unchanged at the end of the reaction Reactions too slow to maintain life Need them Can’t increase temperatures/pressure in cells (fatal)

  7. Molecule Geometry • Substrate molecule fits into the enzyme like a lock & key. • Enzyme shape distorts or changes other factors to make the reaction happen • However certain substances canbind to the enzyme at sites other than the active site and modify its activity (inhibitors/co-factors) • Idea that the enzyme is flexible (induced fit)

  8. Activation Energy • In a ‘natural’ reaction the product has a lower energy than the substrate so equilibrium will take it in the direction of the product. • However there is an energy ‘barrier’ to be overcome • Enzymes lower the activation energy required to bring about a reaction. • Activation energy- the minimum amount of energy needed to start a reaction

  9. High energy intermediate Activation energy Energy Substrates Products Progress of reaction

  10. Enzyme activity Temperature pH Four Variables Enzyme Concentration Substrate Concentration

  11. Optimum Condition Enzymes function best or are most active in specific conditions known as optimum conditions.

  12. Temperature 5- 40oC Increase in Activity 40oC - denatures Rate of Reaction 0 10 20 30 40 50 60 <5oC - inactive

  13. pH Narrow pH optima Disrupt Ionic bonds - Structure Rate of Reaction Effect charged residues at active site 1 5 7 8 9 2 3 4 6

  14. Enzyme Concentration Rate of Reaction Enzyme Concentration

  15. Substrate Concentration Active sites full- maximum turnover Rate of Reaction Substrate Concentration

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