Question

Formation of enzyme-substrate complex (ES) is the first step in catalysed reactions. Describe the other steps till the formation of the product.

Answer 1

Binding of substrate with enzyme

The substrate binds to the active site of the enzyme and the ES [Enzyme-Substrate] complex is formed.

Changes in enzyme and substrate structure

• Substrate binding induces the enzyme to alter its shape thus fitting more tightly around the substrate.
• The molecule of substrate undergoes chemical changes, i.e., breakage of old bonds and formation of bonds. The energy released helps lower the activation energy.
• The transformation of a substrate into a product goes through the pathway called ‘transition state’.

Formation of product

• Finally, the product is formed [EP, Enzyme-Product complex] which is then released from the active site of the enzyme.
• The enzyme is available for another round of reaction.

Schematic representation of the steps involved in enzyme reaction