There is another class of aldolase enzymes known as Class II. These enzymes are found in fungi, algae, and some bacteria. This class differs for Class I in that these enzymes do not have a Lys residue associated with their active sites, but contain a divalent cation (usually Zn2+ or Fe2+) in the active site. Outline a possible mechanism for a Class II aldolase and explain the function of the metal ion in the reaction.