Enzyme Kinetics - Plot of V vs [S]

Plot of V vs [S]

The size of both constants,

and

, is characteristic of the combination of enzyme and substrate. A simple physical interpretation of what the

means is not so simple.

If we plot V vs [S] we get a curve of the type

During the first order phase, at low [S], the enzyme is not saturated with substrate and some of the active sites are open. Thus, as we add more substrate, the rate increases.
During the zero order phase there is a high concentration of substrate and the enzyme is saturated with substrate. Since there are no free active sites, increasing the [S] does not increase the rate of the reaction.

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