| Abstract: | ![]()
Abstract— Previous information about the spectral and photochemical properties of phytochrome in vitro has apparently been determined in large part with chromopeptides derived from the native molecule by proteolysis. Characterization of high-mol-wt phytochrome in vitro has led to the observation that the far-red-absorbing form (Pfr) may undergo relatively large and reversible changes in far-red extinction. Phytochrome preparations which exhibit reduced far-red extinction as Pfr also exhibit a rapid reappearance of red absorbance after discontinuing the red illumination used to establish photostationary equilibrium. This rapid change in the red spectral region is not accompanied by any equivalent absorbance change in the far-red. The molecular basis for these newly reported spectral properties is not known. However, both properties may be eliminated by the addition of either 2-mercaptoethanol or ethylenediaminetetraacetic acid. |
