In an enzyme-catalyzed reaction, what is the starting substance called?

In an enzyme-catalyzed reaction, the starting substance is referred to as the substrate. This is the molecule that the enzyme acts upon to facilitate a biochemical reaction. Enzymes lower the activation energy required for a reaction to occur, thereby increasing the rate of the reaction with the substrate.

The substrate binds to the active site of the enzyme, forming an enzyme-substrate complex. This interaction is vital for the catalytic process, where the substrate is transformed into products. Once the reaction occurs, the enzyme releases the products, which are different molecules than the substrate but are formed through the process facilitated by the enzyme.

Understanding this concept is fundamental as it highlights the specificity of enzymes towards their respective substrates and underscores the role of enzymes in biochemical processes.