Biochemistry
Enzyme
A protein that catalyzes (speeds up) specific biochemical reactions without being consumed in the process. Enzymes make reactions occur millions of times faster than they would otherwise.
Biological Context
Digestion, DNA replication, metabolism—virtually all biological processes depend on enzymes. Each enzyme typically catalyzes one specific reaction, binding to specific substrates. Enzyme activity is regulated by temperature, pH, and molecular signals, allowing cells to control their chemistry.