Figure 3. Toxic metals (M _tox.) interfere with the metabolism of essential, nutrient metals (M _nut.).

The influence of a toxic metal will vary depending on the metabolism. For example, metabolism 1 and metabolism 2 could be aerobic respiration, nitrate reduction, sulfate reduction, and photosynthesis. Similarly, other metals (I) can serve as antimetabolic inhibitors of respiratory enzymes, competing with substrate (S _red) for binding and turnover to product (S _ox). Depending on the inhibitory potency of the toxic metal (M _tox.), the requirements of the essential metal (M _nut.), and the inhibitory potency of a respiratory inhibitor (I), different metabolisms will have different environmental ranges in response to metal gradients.