Final answer:
Significant alterations in pH or temperature can cause enzymes to denature, which leads to a permanent change in their conformation and a reduction or loss in their catalytic activity.
Step-by-step explanation:
When an enzyme's conformation is significantly altered due to changes in pH or temperature, it can lead to the enzyme denaturing. Denaturation results in a permanent loss of the enzyme's three-dimensional structure, which is crucial for its function. For enzymes, there is an optimal pH and temperature range in which they operate most effectively.
Deviating from these conditions can disrupt the chemical bonds in the active site, leading to a decreased capacity to bind substrates and a reduction in enzyme activity. Significant shifts in pH can irreversibly alter the enzyme's structure, while temperatures outside the optimal range cause enzymes to unfold, thereby reducing their ability to catalyze reactions.