What do catalysts, like enzymes, do to chemical reactions?
These catalyze chemical reactions.....
The enthalpy change of a given chemical reaction is more or less constant...
A catalyst HAS no effect on the enthalpy change of a given reaction. A catalyst CAN act to reduce the activation enthalpy of a given reaction, by providing an alternative reaction pathway.
Enzymes are biological catalysts....and as do all catalysts, they make the attainment of equilibrium MORE swift.