Figure 6.8 Dimensionless flux
2 through a two step pathway (6.22) as a function of the ratio
In both cases
is given by (6.24), and the parameters of (6.25) are
a. r, given by (6.23a).
b. r, given by (6.23b).
We can conclude the following:
If both rate constants are multiplied with the same factor/the flux
through the pathway
also increases by a factor
The shape of
does not change, since
is only a function of
x. For large values of
becomes proportional to
If 5 is doubled the value of all parameters a, b and c will decrease by a factor 2, and
as determined from (6.28) will have a different shape.
will increase faster with x,
but the initial slope
+ 1 )1
will only increase by a factor 2 if
is much greater than 1.
does not react proportionally to a change in ,v.
These observations originate in the form of r,
In (6.23a) the parameters of
have no influence
at all on the flux. With (6.23b) the control of the flux is distributed between the two reactions,
and it moves towards the second reaction when
, increases, since a larger value of
leads to a
higher value o f
in (6.28), and this influences r, negatively through the denominator term with v.
The smaller the value of
the faster is step two of the sequence, and
is removed fast enough to
avoid a build up of 5) waiting to be processed by step two.
It now appears that the question of flux control by either step 1 or 2 in the sequence depends on