How Substrate Concentration Affects Reation
Rate
The graph shows that when the concentration of enzyme is maintained
constant, the reaction rate will increase as the amount of substrate is increased.
However, at some point, the graph shows that increasing the amount of substrate
does not increase the reaction rate. The line begins to level off and stay level
at B on the graph. We call this Vmax or the maximum
velocity of reaction.
What happens is this.....
At first there is very little substrate and a lot of enzyme.
An increase in the concentration of substrate means that more of the enzyme
molecules can be utilized. As more enzymes become involved in reactions, the
rate of reaction increases. At some point near B,
all the enzymes are being involved in reactions. When this happens, some of
the substrate must "wait" for enzymes to clear their active sites
before the enzyme can fit with them (like a "lock and key"). After
point B, the reaction rate remains flat because
increasing amounts of substrate must wait before they can fit with their enzyme.
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