[Photoinduced changes in adsorption at 800 nm related to photosystem I functioning].
The spectra and kinetics of light-induced absorbance changes in the near-infrared region of subchloroplast fragments enriched by P700 were studied. An increase in absorbancy within the region of 725--900 nm upon illumination was characterized by a maximum around 810 nm and by "shoulders" around 760 and 870 nm. Similar effects of thermal inactivation and low temperatures on the duration of dark recovery of light-induced absorbance changes at 700 nm and within the region of 725--900 nm suggest that the absorbance changes in the near-infrared region are due to photooxidation of P700. The values of P700 differential extinction coefficients at 810 nm are 8,2.10(3) M-1.cm-1 for digitonin fragments and 7,7.10(3) M-1.cm-1 for fragments prepared with the use of diethyl ester. It was shown that the value of midpoint oxidation-reduction potential measured for the absorbance changes at 810 nm (+492 mv) is higher than that measured at 700 nm (+475 mv).
D004072:Digitonin; D004579:Electron Transport / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D010788:Photosynthesis; D013055:Spectrophotometry, Infrared; D013057:Spectrum Analysis
D004072:Digitonin
Fotoindutsirovannye izmeneniia pogloshcheniia pri 800 nm, sviazannye s funktsionirovaniem fotosistemy I.