Enzymes may be used many times, they have a high turnover rate. Enzymes can be regulated. They can be speeded up or slowed down. Enzymes have an active site which is only a small portion of the entire molecule. In the enzyme carboxypeptidase only 7 out of 305 amino acids are part of the active site.
Several factors affect enzymatic activity.
Temperature increase activity-up to a point. Beyond that point the enzyme begins to denature. Each enzyme has its own pH optimum.