What are proteins that act as biological catalysts called?

Proteins that act as biological catalysts are called enzymes. Enzymes facilitate biochemical reactions by lowering the activation energy required for the reaction to occur, which speeds up the process significantly. This catalytic function is crucial in biological systems as it allows essential reactions to happen at rates conducive to life.

Enzymes are highly specific, meaning that each enzyme typically catalyzes a specific reaction or set of reactions. They work by binding to substrates (the reactants in the reaction) and transforming them into products. This ability to catalyze reactions is vital in various processes such as digestion, metabolism, and DNA replication, among others.

In contrast, hormones are signaling molecules that regulate physiological processes in the body, antibodies are proteins produced by the immune system to neutralize pathogens, and receptors are proteins that receive and transduce signals from outside the cell. While these proteins play critical roles in biological systems, they do not function as catalysts in the same way that enzymes do. Thus, the defining feature of enzymes as biological catalysts clearly differentiates them from the other types of proteins mentioned.