The enzymes given in the problem are used in several reactions in glycolysis. Aldolase, for example, is an enzyme that is involved in the hydrolysis of fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. Thus, it is not an isomerase (i.e. does not catalyze isomerization).
Which of the following enzymes catalyzes an aldose to ketose isomerization?
A. Phosphoglycerate mutase
C. Phosphohexose isomerase
D. Glyceraldehyde-3-phosphate dehydrogenase