Which part of an enzyme is responsible for binding the substrate?

The part of an enzyme responsible for binding the substrate is the active site. The active site is a specific region of the enzyme where the substrate molecules fit and interact. This area has a unique shape and chemical environment that allows for precise binding, which is essential for the enzyme to facilitate a chemical reaction.

When the substrate binds to the active site, it forms an enzyme-substrate complex that stabilizes the transition state of the reaction, leading to the formation of the product. The specificity of the active site ensures that only particular substrates can bind, which is crucial for the enzyme's function and the regulation of metabolic pathways.

In contrast, the allosteric site is involved in the regulation of enzyme activity, but it does not bind the substrate. The binding pocket could refer to a general area of binding, but it does not denote the specific site where substrate interaction takes place as accurately as the term active site does. The reaction center typically relates more to the actual site of the chemical reaction rather than the binding interaction with the substrate.