XP-V is caused by a defect in the translesion DNA polymerase, Pol n. The gene encoding Pol n is sometimes called XPV

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#Unit 1. Molecules and their Interaction Relevant to Biology

The simplest forms of competitive inhibition considered are sometimes termed linear competitive inhibition because both primary and secondary plots are linear. 

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#Unit 1. Molecules and their Interaction Relevant to Biology

In more complicated systems, the primary plots may be linear but the secondary plots non-linear. For example, if not one but two molecules of inhibitor can bind to the substrate binding site, then parabolic competitive inhibition is said to occur, because of the shape of the secondary and Dixon plots.

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#Unit 1. Molecules and their Interaction Relevant to Biology

Similarly, if the inhibitor binds to a different site from the substrate and reduces the affinity of the enzyme for the substrate without altering the reaction characteristics of that substrate which does bind, then hyperbolic competitive inhibition results

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#Unit 1. Molecules and their Interaction Relevant to Biology

Dixon plot for competitive inhibition

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#Unit 1. Molecules and their Interaction Relevant to Biology

TLS Online TPP Program

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#Unit 1. Molecules and their Interaction Relevant to Biology

Uncompetitive inhibitors bind only to the enzyme-substrate complex and not to the free enzyme.