Non-competitive inhibitor

A non-competitive inhibitor binds to an enzyme in another place other than its active site. This results in a change in the enzymes structure so that it is no longer complimentry to its substrate and therefore reduces its catalytic activity. 

The effects of a non-competitive inhibitor can be depicted by changes in its Michaelis-Menten graph:

• K_m is unaltered as the affinity with which substrates bind to the enzyme stays the same.
• V_max decreases because rate of reaction decreases due to the fact that as the reaction progresses, the concentration/amount of effective enzymes decreases.