Cofactors and Coenzymes

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Cofactors and Coenzymes
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Cofactors

• Groups or molecules (other than amino acid
  residues) which are important to catalysis
• Metals
• Coenzymes
• If tightly bound, it is called a prosthetic group
• Enzyme without prosthetic group (cofactor)
• Apoenzyme
• Enzyme with prosthetic group (cofactor)
• Holoenzyme

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Catalysis by Coenzymes

• Some common coenzymes Transfers
• Oxidation/Reduction
• Nicotinamide Adenine Dinucleotide (NAD)
• Flavin Adenine Dinucleotide (FAD)

• Hydride ion (H-)
• Electrons

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Catalysis by Coenzymes

• Some common coenzymes
• One carbon metabolism
• Biotin
• Tetrahydrofolate

Transfers CO2 One carbon groups
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Catalysis by Coenzymes

• Some common coenzymes
• Acyl groups and others
• Coenzyme A
• Lipoic acid
• Thiamine pyrophosphate
• Pyridoxal phosphate
• 5-Deoxyadenosyl-cobalamin

Transfers Acyl groups Acyl groups Aldehydes Amino
groups and amines Alkyl groups
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Vitamin Derived Coenzymes
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Vitamin Derived Coenzymes
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Examples of Coenzyme Catalysis

• Uncatalyzed reaction

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Examples of Coenzyme Catalysis

• Catalysis with pyridoxal phosphate (Vitamin B6
  derivative)

Schiff Base
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Examples of Coenzyme Catalysis
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Examples of Coenzyme Catalysis
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Examples of Coenzyme Catalysis

• Nicotinamide adenine dinucleotide and alcohol
  dehydrogenase

NADH
NAD
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Examples of Coenzyme Catalysis
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