BIOCATALYSIS

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BIOCATALYSIS
4.4 Enzyme classification
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Objective

• At the end of the lesson student should be able
  to
• describe enzyme classification according to IUB
  or as classes of reaction

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Classification of Enzyme according to IUB
(International Union of Biochemistry)

• There are six major classes of enzyme

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1. Hydrolase

• Catalyse the hydrolytic reactions
• E.g Digestive enzymes (lipase,
  amylase, sucrase, peptidase,
  phosphatase
• Sucrose H2O ------------gt glucose
  fructose

Sucrase
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• 2. Oxidoreductases
• Catalyse redox reactions (biological oxidation
  and reduction reactions) by the transfer of
  hydrogen, oxygen or electrons from one molecule
  to another
• Eg dehydrogenase, oxidase, catalase
• Glucose oxydase
• Glucose oxygen -------? gluconic acid
  water

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Catalase
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• 3. Lyase
• - Breaks/add functional group to the
  substrate molecule
• E.g. decarboxylase carboxylase
• Pyruvic --------------gt acetaldehyde
  acid
• CO2

Pyruvic decarboxylase
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• 4. Transferase
• - Transfer functional group (e.g.
  methyl, amino, phosphate) of substrate
  molecule to another
• Glycogen --------------gt glucose-1 phosphate

Glycogen phosphorylase
ATP
ADP
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• 5. Isomerase
• Catalyses the rearrangement of atoms within a
  molecule coverting one isomer to another
• Glucose-6-phosphate ---------gt
  fructose-6- phosphate

• phosphoglucoisomerase

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• 6. Ligase
• - Joins 2 substrate molecules with ATP.
• E.g. synthetase
• ATP AMP Pi
  Pi
• Amino acid tRNA --------------gt
  aminoacyl- tRNA complex
  Aminoacyl-tRNA synthetase

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The Classification Of Enzymes
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Summary of Enzyme classification IUB Convention
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