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ADP-arsenate. Formation by submitochondrial particles under phosphorylating conditions
The Journal of Biological Chemistry
|June 25, 1981
Summary
Arsenate uncouples oxidative phosphorylation by forming ADP-arsenate, which rapidly hydrolyzes. This arsenate compound also reacts with glucose to form glucose 6-arsenate, impacting cellular energy pathways.
Area of Science:
- Biochemistry
- Mitochondrial function
Background:
- Oxidative phosphorylation is crucial for cellular energy production.
- Arsenate is known to interfere with cellular metabolism.
Purpose of the Study:
- To elucidate the mechanism by which arsenate uncouples oxidative phosphorylation.
- To investigate the biochemical fate of arsenate within mitochondria.
Main Methods:
- Utilized submitochondrial particles from beef heart mitochondria.
- Energized particles with succinate to observe ADP-arsenate synthesis.
- Assessed the reaction of ADP-arsenate with glucose in the presence of hexokinase.
- Measured the hydrolysis rate of glucose 6-arsenate.
Main Results:
- Submitochondrial particles synthesized ADP-arsenate from ADP and arsenate when energized.
- ADP-arsenate rapidly hydrolyzed, indicating its role in uncoupling oxidative phosphorylation.
- In the presence of hexokinase, ADP-arsenate formed glucose 6-arsenate.
- Glucose 6-arsenate hydrolyzed with a rate constant of 5.5 X 10(-4) s-1 and served as a substrate for glucose-6-phosphate dehydrogenase.
Conclusions:
- The rapid hydrolysis of ADP-arsenate is the primary mechanism for arsenate-induced uncoupling of oxidative phosphorylation.
- Arsenate can be incorporated into glucose metabolism, forming glucose 6-arsenate, which is further metabolized.