Computer Analysis of Steady State Models of Enzyme Networks
79
------- -~- ~-- - - - - - -------~-~S6
I
~
I
Fig. 1. Test System
The system consists of 10 reversible enzymes all having identical parameters
except for enzyme El which is subject to non-competitive inhibition from 56.
External substance X, is converted via the system into either X 2 or X 3 , the branch
point occurring at metabolite S4.
With the given parameters, which have no particular significance, the system
settles to a steady state with the flux divided equally between the two branches,
as would be expected, and with E, inhibited by 50/;;.
Discussion
At present the methods described have been applied only to test systems
of order 10 enzymes; one such system is shown in figure 1. The result of
asking for "coefficients" on this simple system is shown in Table I, where
it can be seen, for example, that B7 has the greatest degree of control, 46/;;,
over fluxes in the main pathway.
The sum of the coefficients in anyone column can be seen to be
approximately 100 and this has turned out to be a rather general property
of steady state enzyme systems (in preparation).