Abstract

Adenosine triphosphate (ATP) provides energy to all forms of life. It is synthesized by a membrane protein complex, ATP synthase, comprised of two portions, the soluble F1 and the membrane embedded Fo. The synthesis of ATP comes about from the transformation of an electrochemical gradient which in turn facilitates mechanical energy and ultimately chemical energy once ATP is synthesized. Rotation of the c10 ring of the embedded Fo is a result of the electrochemical gradient created from a difference in the concentration of H+ across the membrane between the cytoplasm and external compartment within the cell, prompted by the electron transport chain. The movement of H+ is understood to be through half-channels within the stator of Fo. However, the detailed mechanism of the rotation of the Fo motor remains unknown. Cryogenic electron microscopy has provided medium resolution structures of F1Fo ATP synthase, but the inconsistency between structural data and previous cross-linking data within subunit a suggests the existence of multiple conformations for subunit a. To date, both aY263C and the double mutation aV86C/aL161C have been grown and utilized using site directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) to probe information regarding mobility and rotameric states.

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