Biology 9700 · AS & A Level · Mode of action of enzymes

Mode of action of enzymes — practice question

Catechol is a chemical present in several fruits. The enzyme catechol oxidase can oxidise catechol into a quinone. Parahydroxybenzoic acid (PHBA), which has a structure similar to catechol, inhibits catechol oxidase. Phenylthiourea (PTU) also inhibits catechol oxidase by binding to a copper atom in the enzyme. In what way do both of these inhibitors lower enzyme activity?

  • A1, 2 and 3
  • B1 only
  • C2 only
  • D3 only

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