page_title: Efraim Racker
section_title: Discovery
hierarchical_section_title: Efraim Racker / Discovery
context_page_description: Efraim Racker was an Austrian biochemist who was responsible for identifying and purifying Factor 1, the first part of the ATP synthase enzyme to be characterised. F1 is only a part of a larger ATP synthase complex known as Complex V. It is a peripheral membrane protein attached to component Fo, which is integral to the membrane.
context_section_description: Racker and his associates, Anima Datta, Maynard Pullmand, and Harvey Penefsky, worked to isolate the enzymes involved in ATP synthesis.  They observed that isolated mitochondrial fragments were capable of respiration but not able to synthesize ATP. Racker and his co-workers concluded that oxidative phosphorylation could be restored by addition of the supernatant from the centrifuging.  The complex making this restoration possible was named Factor 1 or F1 as it is a necessary coupling factor for ATPase activity.  This discovery of the first enzyme of oxidative phosphorylation was identified and purified in 1960.
  The factor that binds F1 to the membrane, Fo, was discovered later in conjunction with Yasuo Kagawa.  This particle was found to be sensitive to the antibiotic oligomycin and thus named Fo.  This discovery had the added benefit of silencing any critics of the role of F1 in oxidative phosphorylation because it conferred oligomycin sensitivity on the ATPase activity complex.
  Once both of these factors were identified Racker was able to confirm Peter D. Mitchell's hypothesis that contrary to popular opinion, ATP synthesis was not coupled to respiration through a high-energy intermediate but instead by a transmembrane proton gradient.
  F1 is a critical part of ATP synthesis within the mitochondria.  In its absence, Complex V is not able to create the proton gradient necessary to produce ATP. It is responsible for coupling the oxidation of nutrients to the synthesis of ATP from ADP and inorganic phosphates.
  In September 6, 1991, Racker was felled by  a severe stroke, and died in Syracuse three days after.
caption: ATPsynthase http://www.atpsynthase.info/Basics.html
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