What characteristic makes enzymes specific in their function?

Enzymes exhibit specificity in their reactions primarily due to their precise three-dimensional structures, which allow them to bind only to particular substrates. This characteristic is rooted in the shape and chemical properties of the enzyme's active site, which is complementary to a specific substrate. When a substrate fits into an enzyme like a key into a lock, the enzyme facilitates a specific biochemical reaction.

The statement about enzymes not binding to other substrates emphasizes this selective interaction, as enzymes are designed to catalyze particular reactions based on their unique active sites. This ensures that each enzyme functions optimally within specific pathways of metabolic processes, maintaining the regulation and efficiency essential for biological systems.