The induced fit theory describes how enzymes work or bond with substrates. According to this theory, when a substrate molecule enters the active site of an enzyme, it induces a conformational change in the enzyme's structure. This change brings the enzyme's catalytic site into close proximity with the substrate molecule, allowing the enzyme to catalyze a chemical reaction.

The induced fit theory is supported by a number of experimental observations. For example, studies have shown that the binding of a substrate molecule to an enzyme changes the enzyme's absorption spectrum, indicating that a conformational change has occurred. Additionally, studies have shown that the rate of an enzyme-catalyzed reaction increases as the temperature increases, which is consistent with the idea that the enzyme must undergo a conformational change in order to bind to the substrate molecule.

The induced fit theory is a useful model for understanding how enzymes work. It provides a conceptual framework for understanding how enzymes are able to catalyze reactions with such high efficiency and specificity.