Enzymes - Supercatalysts

• Discovery
  • Spallanzani (1780) - digestive juices of birds break down meat
  • Berzelius (1836) - fermentation must involve catalysis
  • Wohler (1828) - chemical synthesis of urea
  • Buchner (1897) - cell-free, enzymatic fermentation
  • Northrop (1930) - enzymes are proteins
• Terms
  • Substrate - molecule acted on by enzyme
  • Active site - location in the enzyme where the reaction catalysis occurs
• Specificity
  • Speed increase by up to a trillion fold
  • Specific for substrates (molecules enzymes work on) - Box 2.1
  • Lock and Key (Fischer)
  • Induced fit (Koshland) - Figure 2.6
• Structures
  • 20 amino acids
  • Disulfide bonds (between cysteines)
  • Hydrogen bonds
  • Hydrophobic amino acids "inside" enzyme
  • Hydrophilic amino acids "outside" enzyme
• Enzyme Classes
  • Reduction/oxidation (REDOX) - Box 2.3.1
  • Transferases - Box 2.3.2
  • Hydrolases - Box 2.3.3
  • Lyases - Box 2.3.4
  • Isomerases - Box 2.3.5
  • Ligases - Box 2.3.6
• Coenzymes
  • Ions - Fe, Mg, Mn, Zn
  • Vitamin precursors - NAD, FAD
• Lysozyme
  • Discovery - Fleming
  • Structure - Figure 2.8
  • Binding of substrate - Figure 2.11
• Industrial enzyme production
  • Animals - pepsin, trypsin, chymotrypsin, lipases, amylases
  • Plants - papain
  • Microbes - thermophiles
• Energetic Mechanism
  • Lowered activation energy - Box 2.5
• Enzymes
  • Amylases - breakdown of carbohydrates in grain
  • Pectinases - breakdown of pectins in fruits and vegetables
  • Biodetergents - hydrolytic enzymes / subtilisin
  • Proteases - tenderizing beef (papain) (Figure 2.18)
  • Serine Proteases (Figure 2.17)
• Technologies
  • Immobilizing enzymes
    • Glucose isomerase - making fructose corn syrup (Figure 2.31)
    • Lactase (Figure 2.34)
    • Immobilized vs. soluble enzyme costs (Figure 2.32)
  • Protein engineering
    • Subtilisin (Box 2.9 showing oxidation)
  • Immobilizing cells (Figure 2.36)
  • Enzyme membrane reactors (Figure 2.37)