From Creatures Wikia
Chemical reactions are genes which control the changing of one group of chemicals to another. These reactions can be found in the creature's Digital DNA as part of their biochemistry. The main limitation on these is that it is not possible to create a reaction of the form [Nothing] --> Chemical (the reverse is possible). Some of these reactions can be mutated to devastating effect, e.g. converting energy into glycotoxin.
The basic form of a chemical reaction in the genes can be written as iA + jB → kC + lD at a given rate, where ijkl are ratios and ABCD are chemicals. In addition to this basic form, A + B → C ('fusion'), A → NONE (exponential decay), A + B → A + C (catalysis) and A + B → A (catalytic breakdown of B) are possible.
The rate at which reactions occur is concentration-dependent.
As chemicals have no innate properties of their own, stoichiometry is entirely controlled by genetics - which can lead to energy being created from reducing sex drive, as in the Bacchus mutation, or large amounts of long-term energy being created from disproportionally small amounts of short-term energy, as in the Highlander mutation.