Explain catalytic cycle of an enzyme and describe how pH affect its activity

Catalytic Cycle of Enzyme 
The steps involved in the catalytic cycle of enzyme are as under:

• Substrate binds to the active site of an enzyme, fitting into the active site.

• Shape of the enzyme is altered by the binding of the substrate, and it fits more tightly around the substrate.

• Bond between the enzyme and the substrate is broken and a new enzyme−product complex is formed.

• Product is released from the enzyme, and free enzyme is now ready to enter a new catalytic cycle by binding with a new substrate.
   

The activity of the enzyme is greatly affected by pH. The maximum activity of an enzyme is seen at an optimum pH. At the pH above or below the optimum range, the enzyme gets denatured. So, if an enzyme is submitted to a pH level under which it is denatured there will be no or negligible enzymatic activity.    

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