Non-regulatory Allostery
A non-regulatory allosteric site refers to any non-regulatory component of an enzyme (or any protein) that is not itself an amino acid. For instance, many enzymes require sodium binding to ensure proper function. However, the sodium does not necessarily act as a regulatory subunit; the sodium is always present and there are no known biological processes to add/remove sodium to regulate enzyme activity. Non-regulatory allostery could comprise any other ions besides sodium (calcium, magnesium, zinc), as well as other chemicals and possibly vitamins.
Read more about this topic: Allosteric Regulation