title: The enediolate analogue 5-phosphoarabinonate as a mechanistic probe for phosphoglucose isomerase.
abstract: A stable analogue has been prepared of the enediolate anion believed to occur transiently in the reaction of phosphoglucose isomerase. This compound, 5-phosphoarabinonate, is the strongest known competitive inhibitor of the enzyme (Ki = 3 times 10(-7) M below pH 7). A distinctive pH dependence of binding, also found for two other aldonic acid omega-phosphates, 6-phosphogluconate and 4-phosphoerythronate, involves pertubation of a pKa from 7.0 in the free enzyme to 9.0 in the enzyme-inhibitor complex. This perturbation may reflect a catalytically advantageous increase in basicity which occurs around the transition state of the normal enzymatic reaction.
mesh_terms: D000818:Animals; D001089:Arabinose / Q000494:pharmacology; D005956:Glucose-6-Phosphate Isomerase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009132:Muscles / Q000201:enzymology; D010428:Pentosephosphates / Q000494:pharmacology; D011817:Rabbits; D013329:Structure-Activity Relationship
chemical_list: D010428:Pentosephosphates; D001089:Arabinose; D005956:Glucose-6-Phosphate Isomerase