In glycolysis, which enzyme requires Zn^ 2+ as cofactor?

In the process of glycolysis, specific enzymes require metal ions or coenzymes as cofactors for their catalytic activity.

Hexokinase and Phosphofructokinase are kinase enzymes that catalyze the transfer of phosphate groups from ATP. They typically require $Mg^{2+}$ as a cofactor to stabilize the negative charges of ATP.

Glyceraldehyde phosphate dehydrogenase is an oxidoreductase enzyme that utilizes the coenzyme $NAD^+$ to catalyze its reaction and does not require a metal ion cofactor.

Aldolase, specifically Class II aldolase, is a metalloenzyme that requires a divalent metal ion such as $Zn^{2+}$ as a cofactor to stabilize the reaction intermediates during the cleavage of fructose 1,6-bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.

Thus, aldolase is the enzyme that requires $Zn^{2+}$ as a cofactor.

Answer: Aldolase