In the human body, the cations of magnesium, iron, potassium, and zinc act as to speed up reactions. enzymes coenzymes inorganic catalysts enzyme substitutes

Well, usually catalysts speed up any processes, which are of the chemical type most of the time. So, I would say that in the human body, the cations of magnesium, iron, potassium, and zinc act as inorganic catalysts to help speed up reactions.
Enzymes and coenzymes do not speed up reactions, but rather catalysts do.

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