Electron transfer reactions in photosystem I following vitamin K1 depletion by ultraviolet irradiation.
Photosystem I preparations were irradiated with UV to destroy vitamin K1 in situ. The depletion of vitamin K1 resulted in inactivation of NADP+ photoreduction and introduction of a approximately 220 ms component in the flash generated P700+ rereduction at room temperature. The photoreduction of the terminal FeS centers FA and FB in control and vitamin K1-depleted preparations at 7 K were comparable. The data confirm that vitamin K1 is functionally implicated in primary electron transfer reactions in PS I at physiological temperature, and that the anomalous results at cryogenic temperature may be explicable in terms of a by-pass of the vitamin K1 acceptor site or heterogeneity introduced into the photosystem by quinone removal.
Biggins
J
J
Section of Biochemistry, Brown University, Providence, RI 02912.
Tanguay
N A
NA
Frank
H A
HA
D002734:Chlorophyll / Q000378:metabolism* / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D045342:Light-Harvesting Protein Complexes; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins / Q000378:metabolism* / Q000528:radiation effects; D014466:Ultraviolet Rays; D014812:Vitamin K / Q000378:metabolism* / Q000528:radiation effects; D010837:Vitamin K 1 / Q000172:deficiency* / Q000378:metabolism / Q000528:radiation effects
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D014812:Vitamin K; D002734:Chlorophyll; D009249:NADP; D010837:Vitamin K 1