Competitive vs Non-competitive Inhibition:

Two types of reversible inhibition are:

  • Competitive

  • Non-competitive

COMPETITIVE INHIBITORS:

This inhibitor binds to the same site as the substrate. It therefore competes since both substrate and inhibitor are similar in shape.

Effect on Vmax: it is the same velocity in the presence of competitive inhibitors.

Effect on Km: the Michaelis constant increases in the presence of competitive inhibitors.

NONCOMPETITIVE INHIBITORS:

Occurs when the inhibitor binds to a free enzyme or enzyme substrate complex preventing the substrate from binding to its active site.

Effect on Vmax: it decreases in the presence of noncompetitve inhibitors.

Effect on Km: the Michaelis constant is unchanged in the presence of noncompetitive inhibitors.

Graph 1 showing Michaelis – Menten curves for competitve and noncompetive inhibition:

1

Graph 2 showing Lineweaver – Burk plots for competitve and noncompetive inhibition:

2

References:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/EnzymeKinetics.html

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