Principles of Biochemistry Volume 1 - A. Lehninger 1985

Biomolecules
Enzymes
Each enzyme has a specific pH optimum

Each enzyme is characterized by a specific range of optimal pH values (pH optimum) at which it exhibits maximum activity (Fig. 9-6 and Table 9-5). The shape of the curves describing the dependence of enzyme activity on pH reflects the ability of key proton-donor or proton-acceptor groups in the enzyme's Active Site to transition to the required ionization state at specific pH values. An enzyme's pH optimum does not necessarily coincide with the pH of its normal intracellular environment, which may be either higher or lower than the optimum. Thus, the catalytic activity of an enzyme within Cells can be regulated to some extent by altering the pH of the surrounding environment.

Class="center">Table 9-5. Optimal pH values for selected Enzymes

Enzyme

pH optimum

Pepsin

1.5

Trypsin

7.7

Catalase

7.6

Arginase

9.7

Fumarase

7.8

Ribonuclease

7.8


Last update: 06/08/2026

Editorial and Educational Adaptation: This material has been compiled based on the primary/original source text. The project team performed an editorial review, corrected technical inaccuracies, structured sections, and adapted the content for an educational format.

What was processed:

  • elimination of formatting defects (OCR errors, structural breaks, corrupted characters);
  • editorial organization of content;
  • standardization of terminology in accordance with academic sources;
  • verification of factual statements against the original source text.

All mentions of the author, publication year, and origin of the primary text have been preserved in accordance with the source.