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Plotting
Vi as a function of [S], we find that
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At
low values of [S], the initial velocity,Vi, rises almost linearly with
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increasing
[S].
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But
as [S] increases, the gains in Vi level off (forming a rectangular
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hyperbola).
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The asymptote represents the maximum
velocity of the reaction,
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designated
Vmax
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The substrate concentration that produces
a Vi that is one-half of
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Vmax
is designated the Michaelis-Menten
constant, Km(named after
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the
scientists who developed the study of enzyme kinetics).
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Km is
(roughly) an inverse measure of the affinity or strength of
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binding
between the enzyme and its substrate. The lower the Km, the
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greater
the affinity (so the lower the concentration of substrate needed
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to
achieve a given rate).
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