TRANSITION BETWEEN STEADY STATES 



385 



calculated from a simplified equation based on the assumption that the 

 concentration of the intermediate is so low that Vg is proportional to (B). 

 The error introduced by this assumption is seen to be appreciable, espe- 

 cially at high inhibitions. 



Table 7-2 

 Variation of Transition Time with Inhibition " 



° Noncompetitive inhibition of Eg. The transition times have been corrected for 

 the zero inhibition artifact resulting from the assumption that (B) rises only 90% 

 of the way to (B),, which, of course, cannot be applied to the uninhibited system. 

 l\ = I, T'2 = 2, A'j = 10 m3I. A'a = 5 mM, and (A) = 1 niiV. 



When the intermediate concentration is low so that (B) < K^, the in- 

 tegrated exi^ression for the transition time is: 



At 



A% 



(1 - i)V, 



In 



{V2)i 



(7-73) 



where Vg is the uninhibited rate and (v.^), the inhibited rate. Substitution 

 of (B) and (B); and making the same assumption as previously, that (B) 

 rises 90% of the way to (B)„ gives: 



•J '0.9 



2.3K, 



(1 - i)V, 



(7-74) 



In the particular example chosen, (B) is about one-twentieth oi Ko, so that 

 the approximation is not too inaccurate until the inhibition on E.^ requires 

 a relatively high {B)^ to maintain the rate. 



Variation of the transition time with (A) is shown in Table 7-3. One might 

 expect that the higher (A) and the faster reaction 1, the less would be the 

 transition time, but the opposite is seen to occur. The reason for this is 



