Enzymes

• Amino acid


  Monomer that joins together to form polymers called polypeptides (proteins)
• Polypeptides (proteins)


  • Made up of amino acids
  • Formed by the condensation reaction of multiple amino acids
• Amino acid


  • Has a central carbon atom (alpha carbon)
  • Has four atoms or groups of atoms bonded to the central carbon atom: NH2 (amino group), COOH (carboxyl group), H (hydrogen atom), R (side group)
• R group


  Determines how the amino acid interacts and bonds with other amino acids in the polypeptide
• Essential amino acids


  • 20 different types of amino acids common in all organisms
  • 10 that the human body cannot produce, so must be obtained from the diet
• Polypeptides


  • Made from chains of amino acids
  • Have amino acids at each end of the chain: N-terminal (amino terminal) and C-terminal (carboxyl terminal)
• Peptide bond


  Covalent bond formed between the carbonyl group of one amino acid and the amino group of a second amino acid
• Enzyme


  • Protein that catalyzes chemical reactions
  • Binds to chemical reactants called substrates
• Biological catalyst


  • Substance that speeds up chemical reactions without being used up itself
  • Enzymes can act inside or outside of cells
• Activation energy


  Specific amount of energy needed for a chemical reaction to start
• Enzymes


  • Lower the activation energy of chemical reactions, increasing the rate of the reaction
  • Do this by binding to the substrate and allowing chemical bond-breaking and bond-forming processes to happen more easily
• Active site


  • Specific site on each enzyme where substrates with a complementary shape can bind to form an enzyme-substrate complex
  • Shape of the active site is determined by the tertiary structure of the polypeptide
• Lock and Key model

  The enzyme and substrate fit together perfectly, with the active site as the 'lock' and the substrate as the 'key'
• Induced Fit model


  More dynamic interaction between enzyme and substrate, with the enzyme's structure shifting slightly when they bind to form the enzyme-substrate complex
• Every enzyme only catalyzes 1 specific reaction
• Every enzyme has a specific active site that is complementary to the specific substrate
• The tertiary structure of the polypeptide chain determines the shape of the active site
• Denatured enzyme


  Environmental changes to the tertiary structure of the active site can stop the enzyme from working properly
• Factors affecting enzyme activity

  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
• Increasing temperature


  Increases the kinetic energy of molecules, increasing the chances of enzyme-substrate collisions and the rate of reaction
• Changing pH


  Changes the number of hydroxide and hydrogen ions surrounding the enzyme, affecting hydrogen bonding and ionic bonding and causing the enzyme to denature
• Increasing substrate concentration


  Increases the number of substrate molecules that can form ES complexes, increasing the initial rate of reaction until the enzyme is saturated
• Increasing enzyme concentration


  Increases the number of enzyme molecules available to catalyze the substrate, increasing the rate of reaction