Biology: what is non-competitive inhibition?

Tutoring biology, non-competitive inhibition may be mentioned. The tutor explains it.

In yesterday’s post I explain competitive inhibition.

Non-competitive inhibition is similiar to competitive inhibition in that it hinders enzyme function. The difference is that, with non-competitive inhibition, the inhibitor doesn’t bind to the enzyme’s active site; with competitive inhibition, it does.

A non-competitive inhibitor may be a bulky atom such as a heavy metal, or a bulky molecule. This bulky species will attach itself to the enzyme somewhere other than the active site. However, the enzyme’s function is still impeded by one of two possible ways:

  1. The bulk of the inhibitor, though not occupying the active site, may still make it hard to reach, just as a long vehicle in a parking stall can prevent the use of the stall past it.
  2. The inhibitor may change the chemistry of the enzyme, making it less attractive to its intended substrate.



Biology 12, module 1. Open School BC, 2007.

Mader, S. Inquiry into Life, 11th ed. Toronto: McGraw-Hill, 2006.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

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