title: Inactivation of Escherichia coli acetate kinase by N-ethylmaleimide. Protection by substrates and products.
abstract: Acetate kinase (ATP:acetate phosphotransferase, EC 2.7.2.1) from Escherichia coli exhibited a time-dependent loss of activity when incubated with N-ethylmaleimide at micromolar concentrations. However, prolonged incubation did not eliminate all catalytic activity and generally about 15% of its initial activity remained. When incubated with 7.2 microM N-ethylmaleimide, acetate kinase was inactivated with a rate constant of 0.063 min-1. Adenine nucleotides, ATP, ADP and AMP, protected the enzyme against such inactivation, but acetate up to 3.0 M and in the presence of 0.2 M MgCl2 and acetyl phosphate at 24 mM did not interfere with the rate of inactivation. While both acetate and acetyl phosphate did not affect the protection rendered by AMP, the presence of acetyl phosphate altered ADP protection. However, both substrates prevented ATP from protecting the enzyme. These data suggest that the binding sites for acetate and acetyl phosphate are different from that of the adenosine binding domain, but are in close vicinity to the phosphoryl binding regions of the nucleotides.
mesh_terms: D000084:Acetate Kinase / Q000037:antagonists & inhibitors*; D000085:Acetates / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology*; D010755:Organophosphates; D009943:Organophosphorus Compounds / Q000378:metabolism; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D013997:Time Factors
chemical_list: D000085:Acetates; D010755:Organophosphates; D009943:Organophosphorus Compounds; D000249:Adenosine Monophosphate; C011632:acetyl phosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D000084:Acetate Kinase; D005033:Ethylmaleimide