Smaller keys, larger keys, or incorrectly positioned teeth on keys (incorrectly shaped or sized substrate molecules) do not fit into the lock (enzyme). Only the correctly sized key (substrate) fits into the key hole (active site) of the lock (enzyme). In this analogy, the lock is the substrate and the key is the enzyme. Enzymes are fixed to receive another molecule of substrate and thus enzyme activity continues. Since product has lower free energy, it is released. Subsequently, enzyme-substrate complexes result in the transformation of substrate into the product formation due to activity of reaction sites. According to the particular substrate can be found at active site of particular enzyme forming substrate-enzyme complex.Įnzyme-substrate complex remains in tight fitting and active sites of enzymes are complementary to substrate molecules. A particular lock can be opened or closed by a particular key. Similarly substrate has also got fixed geometrical configuration like that of key. which bind the substrate though above bonds to form a transitional (intermediate) compound called enzyme-substrate complex (ES).Įnzyme is analogous to key, where the geometrical configuration of socket is fixed. The active sites of enzyme have some special groups such as NH 2 COOH, -SH etc. The interaction between substrate and enzyme may be either ionic bonds and hydrogen bonds or Van der Waal forces. This binding action makes both enzyme and substrate stable. The enzyme and substrate forms a complex at the active centre. They act on substrate and forms a complex after interactions with the enzyme is called active center. Mechanism of Enzyme Action :Įnzyme is active in catalytic action of biochemical reaction. Some enzymes require an additional moiety known as cofactors for their biological activity. each enzyme has its own optimum pH, temperature, etc. Moreover, these biocatalysts are highly specific for the reaction as well as other conditions e.g. The catalytic efficiency of an enzyme depends upon its three dimensional conformation.

Enzymes are the large globular proteins with molecular weight ranging from 13,000 to millions Dalton.

Key lock model enzymes