Walther stoeckenius biography of martin
Walther stoeckenius biography of martin johnson.
HOW DO WE KNOW?
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Walther stoeckenius biography of martin
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Can a proton gradient drive the synthesis of ATP?
BACKGROUND Peter Mitchell’s hypothesis that a proton gradient can drive the synthesis of ATP was met with skepticism because it was proposed before experimental evidence supported it.
In the 1970s, biochemist Efraim Racker and his collaborator Walther Stoeckenius tested the hypothesis.
EXPERIMENT Racker and Stoeckenius built an artificial system consisting of a membrane, a bacterial proton pump activated by light, and ATP synthase.
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They measured the concentration of protons in the external medium and the amount of ATP produced in the presence and absence of light.
RESULTS In the presence of light, the concentration of protons increased inside the vesicles, suggesting that protons were taken up by the vesicles.
In the dark, the concentration of protons returned to the starting level.
ATP was generated in the light, but not in the dark.
INTERPRETATION In the presence