title: Is phylloquinone an obligate electron carrier in photosystem I?
abstract: Comparative quantitative analysis of phylloquinone content and photochemically competent P-700 has been performed on photosystem I particles subjected to photolysis with ultraviolet irradiation. Nonirradiated control particles exhibit a phylloquinone/P-700 stoichiometry of 1.9 +/- 0.2. Photolysis of the photosystem I particles induces a progressive depletion of phylloquinone, however, photochemistry as assayed at room temperature by the photooxidation of P-700 is unaffected. These data are not consistent with the assignment of phylloquinone as a functional intermediate at room temperature between P-700 and the iron-sulfur clusters, center A and center B.
mesh_terms: D002734:Chlorophyll / Q000378:metabolism* / Q000528:radiation effects; D004579:Electron Transport; D045342:Light-Harvesting Protein Complexes; D010782:Photolysis; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000378:metabolism* / Q000528:radiation effects; D013696:Temperature; D010837:Vitamin K 1 / Q000502:physiology*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D002734:Chlorophyll; D010837:Vitamin K 1