| Adenosine 5'-triphosphate (ATP) synthase couples the transmembrane electrochemical potential of protons to the synthesis of ATP from adenosine 5'diphosphate (ADP) and inorganic phosphate, providing the main ATP source of almost all higher life on earth. During ATP synthesis, stepwise protonation of a conserved carboxylate on each protein subunit of an oligomeric ring of 10-15 c-subunits drives rotation of the rotor moiety relative to the stator moiety. This rotation couples the energy of an electrochemical gradient to the endothermic synthesis of ATP. This dissertation reports the isolation and crystallization of the 14-membered subunit c ring from the spinach chloroplast enzyme diffracting as far as 2.8 angstroms. Though ATP synthase was previously not known to contain any pigments, the crystals of the c-subunit possessed a strong yellow color. The pigment analysis revealed that they contain 1 chlorophyll and 2 carotenoids, thereby showing for the first time that the chloroplast ATP synthase contains cofactors, leading to the question of the possible roles of the functions of the pigments in the chloroplast ATP synthase. |
