active site
The region of an enzyme that binds a substrate molecule and catalyzes its transformation. Also known as the catalytic site. The image shows a net contour model of the enzyme dihydrofolate reductase with substrates NADP+ (red) and dihydrofolate (yellow) bound to the active site. An active site has the following attributes:
- a high degree of specificity for its substrate(s).
- weak interactions between substrate(s) and regions of the active site lower activation energy by holding the molecule in position for reaction.
- catalytic groups in the active site lower activation energy by activating the substrates for reaction.
- these enzyme-substrate interactions increase the rate of the reaction.
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