Competitive inhibition is a form of enzyme inhibition where binding of the inhibitor to the active site on the enzyme prevents binding of the substrate and vice versa. The presence of a competitive inhibitor increases the Km constant of the enzyme (and not decrease), while it does not affect the Vmax. The competitive inhibitor binds at the active site, so decreases the affinity of the enzyme for its substrate, so Km constant increases. If substrate concentration is increased, inhibition overcomes and attains normal Vmax.
