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Enzymes

Mr. Safford’s Biological Sciences. Enzymes. All enzymes are globular proteins thus spherical in shape Control biochemical reactions in cells They have the suffix " - ase " . What are enzymes?. Intracellular enzymes are found inside the cell

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Enzymes

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  1. Mr. Safford’s Biological Sciences Enzymes

  2. All enzymes are globular proteinsthus spherical in shape • Control biochemical reactions in cells • They have the suffix "-ase" What are enzymes?

  3. Intracellular enzymes are found inside the cell • Extracellular enzymes act outside the cell (e.g. digestive enzymes) • Enzymes are catalysts → speed up chemical reactions • Reduce activation energy required to start a reaction between molecules • Substrate molecules(reactants) are converted into products • Reaction may not take place in absence of enzymes (each enzyme has a specific catalytic action) • Enzymes catalyze a reaction at max. rate at an optimum state What are enzymes?

  4. Lock and key theory • Only one substrate (key) can fit into the enzyme's active site (lock) • Both structures have a unique shape • Enzyme is not used (reusable) up in the reaction (unlike substrates) How Do They Work?

  5. How Do They Work?

  6. Let’s See it in Action! How Do They Work?

  7. Changes in pH • Affect attraction between substrate and enzyme • Ionic bonds can break and change shape → enzyme is denatured • Charges on amino acids can change → Enzyme Substrate complex cannot form • Optimum pH (enzymes work best) • pH 7 for intracellular enzymes • Acidic range (pH 1-6) in the stomach for digestive enzymes (pepsin) • Alkaline range (pH 8-14) in oral cavity (amylase) 3 things that Affect Enzyme Effectiveness

  8. Temperature Increased Temperature • Increases speed of molecular movement →increased chances of molecular collisions → more ES complexes • Enzymes have optimum temp. for their action (usually 37°C in humans) • Just above ≈42°C, enzyme is denatured due to the breaking Hydrogen bonds and higher temps. break covalent bonds • Denaturation -the loss of appropriate structure rendering the enzyme inactive. • Shape is changed → active site can't be used, ever again

  9. Denatured

  10. Decreased Temperature • Enzymes become less and less active, due to reductions in speed of molecular movement • Below freezing point • Inactivated, not denatured • Regain their function when returning to normal temperature

  11. A typical graph of rate against temperature might look like this:

  12. Concentrations of Substrate and Enzyme

  13. The presence of inhibitors • Enzyme inhibitors are substances which alter the catalytic action of the enzyme and consequently slow down, or in some cases, stop catalysis. • three common types of enzyme inhibition – • Competitive-compete for active site • Non-competitive- bind to enzyme somewhere other than the active site and change the active site

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