Besides the amylolytic enzymes, there must also be a glucose-isomerase enzyme in action, and it must be its effect which results in the appearance of fructose.

Phosphoribosylanthranilate isomerase (PRAI) and indole-3-glycerol phosphate synthase (IGPS) are distantly related α/β-barrel enzymes that catalyze successive steps in tryptophan biosynthesis.