Factors Affecting Enzyme Action
The activity of enzymes is strongly affected by changes in pH and temperature. Each enzyme works best at a certain pH left graph and temperature right graph, its activity decreasing at values above and below that point. This is not surprising considering the importance of
tertiary structure i.e. shape in enzyme function and
non covalent forces, e.g., ionic interactions and hydrogen bonds, in determining that shape.
Examples:
the protease pepsin works best as a pH of 12 (found in the stomach) while
the protease trypsin is inactive at such a low pH but very active at a pH of 8 (found in the small intestine as the bicarbonate of the pancreatic fluid neutralizes the arriving stomach contents .Changes in pH alter the state of ionization of charged amino acids e.g., Asp, Lys that may play a crucial role in substrate binding and/or the catalytic action itself. Without the unionized -COOH group of Glu-35 and the ionized -COO- of......
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