Chemistry - Biomolecules Question with Solution | TestHub

Emil Fisher (1894) proposed a 'lock and key' theory to explain the mechanism of enzyme action. According to this theory, the active sites of the enzyme have a specific geometric shape, wherein the substrate molecule gets fitted to form an enzyme–substrate complex. This is like the fitting of a key to a particular lock. According to this theory,

Enzyme + Substrate → Enzyme–substrate complex → Enzyme + Product

This concept can explain how a large quantity of substrates is acted upon by a small concentration enzyme. It also explains, why enzymes remain unaffected after the completion of a bioreaction.