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Hydrolysis of adenyl-5-yl imidodiphosphate by beef heart mitochondrial ATPase
Abstract:
Beef heart mitochondrial ATPase (F1) catalyzes the hydrolysis of the ATP analog adenyl-5-yl imidodiphosphate (AMP-PNP). The reaction products are inorganic phosphate and adenyl-5-yl phosphoramidate (AMP-PN) as determined by HPLC analysis. The hydrolysis occurs in both the presence and absence of added divalent metal ions and is stimulated by potassium. The kinetic properties of the hydrolytic reaction depend markedly on the identity of the added divalent metal. GMP-PNP and AMP-CPP are also hydrolyzed, while AMP-PCP is not. Adenyl-5-yl phosphoramidate is a potent effect of beef heart mitochondrial ATPase activity. Based on these data, a reinterpretation of work based on the assumption that AMP-PNP is not hydrolyzed is presented.
Insights
Beef heart mitochondrial ATPase (F1) hydrolyzes adenyl-5-yl imidodiphosphate (AMP-PNP), producing inorganic phosphate and adenyl-5-yl phosphoramidate (AMP-PN). This finding necessitates reinterpreting previous research that assumed AMP-PNP was not hydrolyzed.
Area of Science:
- Biochemistry
- Enzymology
- Mitochondrial research
Background:
- Beef heart mitochondrial ATPase (F1) is crucial for cellular energy metabolism.
- Understanding its substrate specificity is vital for accurate biochemical analysis.
Purpose of the Study:
- To investigate the hydrolysis of adenyl-5-yl imidodiphosphate (AMP-PNP) by beef heart mitochondrial ATPase (F1).
- To characterize the reaction products and kinetics.
- To re-evaluate prior studies based on new findings.
Main Methods:
- High-Performance Liquid Chromatography (HPLC) analysis to identify reaction products.
- Enzyme kinetic studies with varying divalent metal ions and potassium.
- Testing of related ATP analogs (GMP-PNP, AMP-CPP, AMP-PCP).
Main Results:
- Beef heart mitochondrial ATPase (F1) catalyzes AMP-PNP hydrolysis to inorganic phosphate and adenyl-5-yl phosphoramidate (AMP-PN).
- Hydrolysis is influenced by divalent metal ions and potassium.
- Adenyl-5-yl phosphoramidate was identified as a potent inhibitor.
- AMP-PCP was not hydrolyzed, while GMP-PNP and AMP-CPP were.
Conclusions:
- AMP-PNP is a substrate for beef heart mitochondrial ATPase (F1), contrary to previous assumptions.
- The inhibitory nature of adenyl-5-yl phosphoramidate is a key characteristic.
- Previous research assuming AMP-PNP non-hydrolysis requires reinterpretation.