B. Phosphoglucose Isomerase 1. This reaction requires ring opening followed by isomerization, and subsequent ring closure 3. Proposed reaction mechanism for the PGI reaction involves general acid-base catalysis a. Substrate binding b. A base, presumably the carboxylate group of Glu, abstracts the acidic proton from C2 to form a cis-enediolate intermediate d. Proton is replaced on C1 in an overall proton transfer.
Protons abstracted by bases are labile and exchange rapidly with solvent protons.
PFK plays a central role in control of glycolysis because it catalyzes one of the pathway's rate-determining reactions D. Aldolase 1. Logic of reaction 2 is made evident in the aldol cleavage between C3 and C4 of FBP which requires a carbonyl at C2 and a hydroxyl and C4 3. I occurring in animals and plants 1. Aldolase is stereospecific with four possible resulting products depending on side of attack E. Triose Phosphate Isomerase 1. GAP is the only product of the aldol cleavage reaction that continues along the glycolytic pathway 2.