Country: United States
Date: January 2005
How is the reversibility of an enzyme
controlled? What determines whether it will make a product or
The enzyme does not affect the equilibrium of the reaction, that is, the
ratio of substrate to product. If an enzyme is added to a solution of S it
will produce P until the equilibrium ratio of S/P is attained. If enzyme is
added to a solution of P, it will produce S until the same equilibrium
ratio is attained . At equilibrium, the rate of formation of P from S is
the same as the rate of formation of S from P in terms of moles/unit time.
In short, the direction that the enzyme catalyzes depends on how far away
from equilibrium the reaction is.
Ron Baker, Ph.D.
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Update: June 2012