How does the lock and key mechanism help enzymes to increase the rate of substrate reactions in the body?

Enzymes are proteins that typically help to increase the rate of specific reactions in the body, each enzyme is specific to one or two substrates meaning that different enzymes help to increase the rate of different reactions. This is achieved through the lock and key mechanism as only a specific substrate (the key) will fit into the active site (lock) of its corresponding enzyme (diagram).The lock and key mechanism increases reaction rates by reducing the initial energy needed for a reaction to happen between two substrates (the activation energy). This is because enzymes can hold all substrates needed for a reaction in their active sites which allows them to come close together in the correct orientation, meaning that less kinetic energy is required to cause the two substrates to interact. Enzymes can also work by reducing movement of the substrates and providing charged structures within their amino acid structures to stabilise the transition states of the substrates which are reacting.