Factors that affect enzyme action — common mistakes

When explaining effects, always link the factor to the active site's specific shape and the formation of enzyme-substrate complexes. For denaturation, explicitly state which bonds are affected (hydrogen/ionic) and that the change is irreversible. For inhibitors, be clear about where they bind (active vs. allosteric site) and whether they can be overcome by adding more substrate.

Enzyme action in Cambridge 9700 Biology is primarily affected by temperature, pH, substrate concentration, enzyme concentration, and inhibitors. Each factor influences the enzyme's active site structure or the frequency of successful collisions, ultimately determining the rate of the catalysed reaction. Our free course delves deeper into each of these, complete with past paper examples.

Enzyme denaturation is the irreversible loss of an enzyme's specific three-dimensional structure, particularly its active site, often caused by extreme temperatures or pH. It's crucial because a denatured enzyme can no longer bind to its substrate and therefore loses its catalytic function, which can have severe consequences for metabolic pathways and organism survival.

At high substrate concentrations, enzyme activity plateaus because all available enzyme active sites become saturated with substrate molecules. The enzymes are working at their maximum capacity (Vmax), and even if more substrate is added, there are no free active sites to bind to, so the enzyme concentration becomes the limiting factor.

A competitive inhibitor resembles the substrate and binds to the active site, while a non-competitive inhibitor binds to an allosteric site, changing the active site's shape. Competitive inhibition can be overcome by adding more substrate, but non-competitive inhibition cannot.