A Digital Computer System
for the Construction and Analysis of Steady State Models
of Enzyme Catalysed Networks
J. A. BURNS
With 1 Figure
Abstract
A fairly general method for constructing computer models of enzyme systems
in solutions is described. The method allows for high order systems and for
metabolic inhibition but does not cater for enzyme repression. Both the structure
of the enzyme system and the values of the parameters already in the system can
be readily adjusted. The problem of finding the steady state and of discovering
the rate controlling effect of an enzyme are discussed.-The methods are applied
to some simple systems of order 10 enzymes by way of illustration.
Introduction
A model of a metabolic system will, most naturally, appear as an "interconnection" diagram which displays the important transformations and
influences thought to be present in a real system. The "structure" of the
system is contained in this diagram. Attached to the diagram will be information of a quantitative nature concerning the values of parameters in the
system.
However the problem of "modelling" is not that of writing a single
fixed program and running it with variable data. The model is not a fixed
thing and will, almost certainly, change frequently in the course of an investigation. For example extra enzymes may be added or perhaps an extra
inhibitory effect, "just to see what happens", which may be immediately
removed if it seems of no interest. Furthermore the investigator does not
wish to be tied to a fixed format of operations but needs to be free to adjust
parameters and ask "questions" about the enzyme system with complete
flexibility. A further complication from the point of view of "programming
strategy" is that the questions which the investigator wishes to ask cannot
all be clearly defined in advance, indeed some new "questions" almost
always arise as an investigation proceeds.
The above remarks apply particularly to a situation, such as our own,
where we have a theoretical interest in the properties of enzyme networks,
for the Construction and Analysis of Steady State Models
of Enzyme Catalysed Networks
J. A. BURNS
With 1 Figure
Abstract
A fairly general method for constructing computer models of enzyme systems
in solutions is described. The method allows for high order systems and for
metabolic inhibition but does not cater for enzyme repression. Both the structure
of the enzyme system and the values of the parameters already in the system can
be readily adjusted. The problem of finding the steady state and of discovering
the rate controlling effect of an enzyme are discussed.-The methods are applied
to some simple systems of order 10 enzymes by way of illustration.
Introduction
A model of a metabolic system will, most naturally, appear as an "interconnection" diagram which displays the important transformations and
influences thought to be present in a real system. The "structure" of the
system is contained in this diagram. Attached to the diagram will be information of a quantitative nature concerning the values of parameters in the
system.
However the problem of "modelling" is not that of writing a single
fixed program and running it with variable data. The model is not a fixed
thing and will, almost certainly, change frequently in the course of an investigation. For example extra enzymes may be added or perhaps an extra
inhibitory effect, "just to see what happens", which may be immediately
removed if it seems of no interest. Furthermore the investigator does not
wish to be tied to a fixed format of operations but needs to be free to adjust
parameters and ask "questions" about the enzyme system with complete
flexibility. A further complication from the point of view of "programming
strategy" is that the questions which the investigator wishes to ask cannot
all be clearly defined in advance, indeed some new "questions" almost
always arise as an investigation proceeds.
The above remarks apply particularly to a situation, such as our own,
where we have a theoretical interest in the properties of enzyme networks,