. Bacterial photosynthesis. Bacteria -- Physiology; Photosynthesis. 346 PHOTOMECHANICAL CONSIDERATIONS ESR Signal of TMPD Free Rodical ESR Signal of R. rubrum Chromataphores in the Light. Magnetic Field ȉ Fig. 3. A magnetic field scan of the first derivative ESR signals due to TMPD and R. rubrum chromatophores in the light. The modulation was sufficiently high (4 gauss) to reduce the resolution of the hyperfine lines of the TMPD radi- cal ion so that only the 13 lines which make a larger splitting of gauss are evident (10). The oxygen tension was reduced as described in the text. luminat
. Bacterial photosynthesis. Bacteria -- Physiology; Photosynthesis. 346 PHOTOMECHANICAL CONSIDERATIONS ESR Signal of TMPD Free Rodical ESR Signal of R. rubrum Chromataphores in the Light. Magnetic Field ȉ Fig. 3. A magnetic field scan of the first derivative ESR signals due to TMPD and R. rubrum chromatophores in the light. The modulation was sufficiently high (4 gauss) to reduce the resolution of the hyperfine lines of the TMPD radi- cal ion so that only the 13 lines which make a larger splitting of gauss are evident (10). The oxygen tension was reduced as described in the text. luminated R. rubrum chromatophores, a complex relationship was established. Fig. 3 shows a magnetic field scan of the ESR signals in an anaerobic system containing TMPD and chromatophores in the light. The signals due to both TMPD and the chromatophores show a larger steady state value upon illumination. Light of 880 m^, where only the bacteriochlorophyll absorbs, is effective in this reaction. Taking advantage of the fact that the chromatophore signal is 2 to 3 times as broad as that of the TMPD (9,10), we made preliminary kinetic analyses of the two ESR signals, A span of magnetic field values was chosen where the TMPD first derivative ESR signal changed from one direction to the other, while the light-induced ESR signal from chromatophores had a constant direction. In Fig, 4, each of the curves represents a different magnetic field position arranged so the directions of the two signals first are additive then subtractive. When the light was turned on at an additive point, the total signal was the highest because it combined both signals. In this instance, an increase in ESR signal due to chromatophore is always reflected in the positive direction of the first derivative plot. The curves at the left of the "light-on" series show the increase in TMPD free radical concentration in the positive direction, while the magnetic fields used in those experiments on the right-han
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