The variation of the rate of an enzyme catalyzed reaction with...

The substrate concentration influences enzyme activity. As the substrate concentration increases the rate of reaction also increases. This is because the more substrate molecules will interact with enzyme molecules, the more products will be formed.

However, after a certain concentration, further increase in substrate concentration will have no effect on the rate of reaction, since the substrate concentration will no longer be the limiting factor. At this stage, enzyme molecules become saturated and work at their maximum possible rate.