Inhibition of Fructose‐1,6‐bisphosphate Aldolase from Rabbit Muscle and Bacillus stearothermophilus

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Abstract
Phosphoglycollohydroxamic acid and phosphoglycollamide are inhibitors of rabbit muscle fructose-1,6-bisphosphate aldolase. The binding dissociation constants determined by enzyme inhibition and protein fluorescence quenching suggest that two distinct enzyme inhibitor complexes may be formed. The binding dissociation constants of the two inhibitors to Bacillus stearothermophilus cobalt(II) fructose-1,6-bisphosphate aldolase have also been determined. The hydroxamic acid is an exceptionally potent inhibitor (Ki= 1.2 nM) probably due to direct chelation with Co(II) at the active site. The inhibition, however, is time-dependant and the association and dissociation constants have been estimated. Ethyl phosphoglycollate irreversibly inhibits rabbit muscle fructose-1,6-bisphosphate aldolase in the presence of sodium borohydride, presumably by forming a stable secondary amine through the active-site lysine residue. A new condensation assay for fructose-1,6-bisphosphate aldolases has been developed which is more sensitive than currently used assay procedures.