Enzymes speed up chemical reactions by lowering activation rates. In general, the lower amount of activation energy that a potential reaction has, the faster the rate of reaction will be. Enzymes change shape during the reaction process, which allows them to efficiently reduce activation rates.
When enzymes change shape, the process is referred to as an induced fit. During this process, enzymes essentially undergo physical transformations to bind with other enzymes in chemical reactions. These enzymes fit together with like enzymes to form complete reactions, much like the process of completing a puzzle. Enzymes also contain hotspots, or active sites, which are locations on enzyme surfaces that enable substrates to bind. These sites also serve as host locations for chemical reactions to take place: the spots are hubbubs of activity and act much like train stations or bus terminals, allowing vital exchanges to take place. These chemical reactions occur on the surfaces of enzymes, which is where substrates bind. Enzyme active sites are stabilized by multiple weaker reactions (such as hydrophobic contacts, hydrogen bonds and electrostatic interactions) that ultimately allow them to support rapid chemical reactions. Chemical reactions require an internal change too: this is made possible by the formation of substrates within enzymes, which rise to the surface and bind to active sites.