title: Suicide inactivation of fructose-1,6-bisphosphate aldolase.
abstract: 2-Keto-4,4,4-trifluorobutyl phosphate (HTFP) was prepared from 3,3,3-trifluoropropionic acid. HTFP acts as an irreversible inhibitor of rabbit muscle aldolase: the loss of activity was time dependent and the inactivation followed a pseudo-first-order process. Values of 1.4 mM for the dissociation constant and 2.3 X 10(-2) s-1 for the reaction rate constant were determined. The kinetic constants do not depend on the enzyme concentration. No effect of thiols on the inactivation rate was detected. Only 1-2 mol of fluoride ions was liberated per inactivated subunit, indicative of a low partition ratio. Dihydroxyacetone phosphate protected the enzyme against the inactivation in a competitive manner, and glyceraldehyde 3-phosphate protected as if it formed a condensation product with HTPF. 5,5'-Dithiobis(2-nitrobenzoic acid) thiol titration showed the loss of one very reactive thiol group per enzyme subunit after inactivation. All those observations seem to agree with a suicide substrate inactivation of aldolase by HTPF.
mesh_terms: D000818:Animals; D004099:Dihydroxyacetone Phosphate / Q000494:pharmacology; D005634:Fructose-Bisphosphate Aldolase / Q000037:antagonists & inhibitors*; D066298:In Vitro Techniques; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D010755:Organophosphates / Q000494:pharmacology; D011817:Rabbits; D013438:Sulfhydryl Compounds
chemical_list: D010755:Organophosphates; D013438:Sulfhydryl Compounds; D004099:Dihydroxyacetone Phosphate; C044864:2-keto-4,4,4-trifluorobutyl phosphate; D005634:Fructose-Bisphosphate Aldolase