Explain the difference between competitive and noncompetitive enzyme inhibitors.

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An enzyme is a biological catalyst - in other words it is a protein which speeds up the rate of biological reactions without being used up itself. Enzyme action can be affected by compounds called inhibitors- molecules that bind to the enzyme to decrease its actvity. There are two type of inhibitors; competitive and non-competitive.

Competitive inhibitors are molecules which have similar chemical structure to the enzyme's substrate, and can therefore bind to the enzyme's active site.  Competitive inhibitors 'compete' with the substrate to bind to the active site.

Non-competitive inhibitors bind to an enzymes allosteric site (a binding site separate from the active site). In doing so they change the conformation of the active site, thus preventing the enzyme from binding to its specific substrate. 

Eleanor H.

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