CHARACTERIZATION OF A MICROSECOND INTERMEDIATE IN THE LASER FLASH PHOTOLYSIS OF SMALL PHYTOCHROME FROM OAT |
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| Authors: | Silvia E Braslavsky † J Ioan Matthews † Hans J Herbert † Jacob de Kok† Carel J P Spruit Kurt Schaffner† |
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| Institution: | †Institut für Strahlenchemie im Max-Planck-Institut für Kohlenforschung,D–4330 Mülheim a. d. Ruhr, West Germany†Laboratory of Plant Physiological Research, Agricultural University, Wageningen, The Netherlands |
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| Abstract: | Abstract— Irradiation of small phytochrome from oat in its Pr form with 15 ns laser pulses of different wavelengths(605–655 nm) gave rise to a difference absorption with maxima at 400 and 685 nm for the first detectable transient. Bleaching of a 660 nm band was observed, non-recuperable up to 1 ms. The transient absorption has a lifetime of 70±15 μs at 273 K. The transient is tentatively identified as lumi-R and the conformation of its chromophore is postulated to be more extended than that of Pr. A deviation from the exponential decay of the lumi-R absorption at 284 and 300 K and the lack of observable enhancement of the far-red absorption within 1 ms are interpreted in terms of the appearance of still other intermediates on this time scale between lumi-R and Pfr phytochrome. |
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