Simple Irreversible Inhibition in the Presence of Substrate

Substrate may protect the enzyme from the effects of irreversible inhibitors, and the model has to be modified to take this fact into consideration. 

Consider the interactions of free enzyme with inhibitor and substrate  

The differential equation that describes the formation of irreversible enzyme-inhibitor complex, the dissociation constant for the ES complex, and the mass balance for the enzyme are, respectively. 

Substitution of [Ey] — [E] — [El ] for [ES], and rearrangement, results in the following expression for the concentration of free enzyme  

To obtain an estimate of a k versus [Iq] data set has to be created at a fixed substrate concentration. A plot of this k versus [Iq] data would yield a straight hne (Fig. 5.2). With the aid of standard linear regression procedures, the value of the slope of this line can be obtained. This slope corresponds to 

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TIME-DEPENDENT SIMPLE IRREVERSIBLE INHIBITION IN THE PRESENCE OF SUBSTRATE... 

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