Which enzyme works at an optimum pH of about 2?

  • A. Salivary amylase
  • B. Pepsin
  • C. Trypsin
  • D. Catalase

Explanation

Pepsin is secreted into the stomach where hydrochloric acid keeps the pH near 2, and its structure is stable and active in exactly those conditions. Trypsin works in the small intestine at about pH 8, salivary amylase near neutral, and catalase around pH 7. An enzyme moved far from its optimum pH loses activity because the charges on the R groups in the active site change.

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