Metabolic Flux Bottleneck | mysimulator.uk

Pathway Flux

Overall pathway flux (final product)

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Theoretical max flux

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Final product made

Enzyme activity

Step 1 — E1 activity 60%

Step 2 — E2 activity 90%

Step 3 — E3 activity 30%

Step 4 — E4 activity 100%

Step 5 — E5 activity 80%

How it works

Each chamber is one enzyme-catalyzed step in a linear metabolic pathway. Substrate enters chamber 1 in unlimited supply; every step converts what's waiting in its own buffer into the next intermediate at a rate set by its enzyme's activity slider. A step can only work as fast as (a) its own capacity, and (b) how much substrate is actually waiting for it.

Because every step feeds the next, the whole chain can never produce final product faster than its single slowest step — the rate-limiting step. Molecules pile up in the buffer just before that step (it can't drain them fast enough), while every step downstream sits comparatively empty, starved of material to work on.

Try raising a non-bottleneck enzyme's activity: overall flux barely moves. Raise the highlighted bottleneck step instead, and flux climbs immediately — until some other step becomes the new slowest link.

Metabolite Final product Bottleneck chamber

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Metabolic Flux Bottleneck — Rate-Limiting Enzyme Simulator