Enzyme-substrate complex

Enzyme-Substrate (ES) complexes are formed during enzyme catalysed chemical reactions.

Every enzyme is equipt with a 'cleft' in its structure which is complementary to a particular substrate. This is known as the active site. As well as shape, specificity of the active site is developed further via the amino acid R-Groups within the site. These groups will interact specifically with the substrate molecule(s).[docs.google.com/viewer] The ES complex is the state in which the active site of the enzyme is non covalently bound to the substrate molecule(s). This is where the chemical reaction occurs.

ENZYME + SUBSTRATE -> ENZYME SUBSTRATE COMPLEX -> ENZYME + PRODUCT 

The following is a useful video demonstrating the formation of an Enzyme Substrate Complex: www.youtube.com/watch