Metabolic Engineering: kinetics
The emphasis on the mechanisms of transfer of genetic materials and altering genes by
mutation diverts attention from what is actually happening to the biochemical pathways.
Some points that must not be overlooked are:
- Biochemicals are intermediates. They are formed by some reactions and consumed
or destroyed by other reactions.
- Accumulating a desired biochemical can result from either increasing its rate of
formation or decreasing its rate of disappearance.
- Mutation can be directed toward either the pathways for the desired biochemical or
toward pathways that compete for necessary intermediates.
We have some highly oversimplified computer simulations that reinforce these concepts.
Exercise 1 shows how shifts in the sizes of pools of intermediate
biochemicals affect the concentrations of biochemicals derived in competing pathways.
The reaction sequences are:
Try various permutations with this applet: (RED for D, GREEN for E, BLUE for F)
This is not meaningful by itself, but you see that reactions compete. The concentrations
depend very much on the relative magnitudes of the reaction rate coefficients that were built into the simulation. The main
features of this exercise are:
the time behavior is not realistic because efects such as feedback inhibition are not included, and the concentrations after equilibrium is
established are the point of this exercise,
reducing competition favors accumulation of a desired biochemical.
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bungay@rpi.edu while on sabbatical leave in Porto, Oct. 1996