Enzymes

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Enzymes protein catalysts

• The active site can lower an EA barrier by
• orienting substrates correctly
• straining substrate bonds
• providing a favorable microenvironment
• directly participating in the reaction

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Induced Fit of Substratee.g. carboxypeptidase
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Zn2 - an essential cofactor in carboxypeptidase
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Mechanism of action
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• Competitive inhibitors
• Bind to the active site of an enzyme, competing
  with the substrate

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• Noncompetitive inhibitors
• Bind to another part of an enzyme, changing the
  function

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Examples of allosteric regulation -phosphorylati
on -Ca2/calmodulin
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Cellular Respiration

• C6H12O6 O2 ? 6CO2 6H2O
• forward reaction DG -686 kcal/mol
• reverse reaction DG 686 kcal/mol

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