Which type of proteins function as catalysts in biochemical reactions?

Enzymes are the proteins that function as catalysts in biochemical reactions. They accelerate the rate of reactions by lowering the activation energy required for the reaction to proceed. This catalytic function is crucial for numerous biological processes, including metabolism, DNA replication, and signal transduction. Enzymes are highly specific, meaning that each enzyme will typically catalyze a specific reaction or type of reaction involving particular substrates.

The role of enzymes as catalysts is vital for life because many biochemical reactions would occur too slowly to sustain cellular processes without them. This is why enzymes are often referred to as biological catalysts.

The other types of proteins listed serve different functions. Transporter proteins are responsible for moving molecules across cell membranes, structural proteins provide support and shape to cells and tissues, and receptor proteins are involved in receiving and transmitting signals from outside the cell. While important, these proteins do not function as catalysts.