Скачать или смотреть EFFECT OF PH ON ENZYME ACTIVITY.Chapter 3rd Enzyme of 11th Biology

pH significantly affects enzyme activity, with each enzyme having an optimum pH for maximum function; deviations from this point decrease activity, while extreme pH levels cause denaturation, permanently altering the enzyme's shape and rendering it inactive by disrupting the bonds that maintain its active site. This creates a bell-shaped curve, showing activity rises to the optimum, then drops as pH moves away, with specific enzymes like stomach pepsin (low pH) or small intestine enzymes (higher pH) adapted to their environment.
How pH impacts enzymes
Optimal pH: The specific pH where an enzyme works most efficiently, allowing maximum successful binding with its substrate.
Below Optimum: Lowering the pH (making it more acidic) affects the charges on amino acids, disrupting ionic and hydrogen bonds, which changes the active site shape and reduces substrate binding.
Above Optimum: Raising the pH (making it more alkaline) also disrupts these bonds, altering the active site and slowing the reaction.
Denaturation: Extremely high or low pH levels break the bonds holding the enzyme's tertiary structure, causing the active site to lose its specific shape, preventing substrate binding and leading to irreversible inactivation (denaturation).
Examples in the human body
Pepsin (Stomach): Optimum pH ~1.5-2.5 (highly acidic).
Salivary Amylase (Mouth): Optimum pH ~6.7 (neutral).
Pancreatic Enzymes (Small Intestine): Optimum pH ~8.0 (alkaline, due to bicarbonate).