Speed up reactions by

 

lowering activation energy.

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The active site changes shape after the substrate binds. 

 

This lowers activation energy.

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Substrate                                    Product

High affinity for active site               low affinity for active site

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As the product has low affinity, it leaves the active site allowing another substrate to bind to active site.

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Lower enzyme activity shown indirectly by

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1.  reduce bubbles of gas/foam produced

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2. increasing time of reaction (slowing reaction rate)

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3. reducing/prevent colour change in colorimeter

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​​​​​​​​​Bind at the active site and prevent substrate from binding.

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inhibitor resembles substrate & has high affinity for active site.

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Bind away from active site but change shape of active site preventing substrate from binding.

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Inhibitor does not resemble substrate & has low affinity for active site.

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Inhibition reversible with increasing substrate concentration.

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​​Inhibition not reversible with increasing substrate concentration as active site is destroyed.

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​​When end product reaches a critical concentration, it binds to an earlier enzyme stopping its own synthesis.

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Advantage

Saves ATP/ resources as end product only made when required.

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