Chromophore structure of the physiologically active form (P_fr) of phytochrome

W. Rüdiger*,
F. Thümmler*,
E. Cmiel†, and
S. Schneider†

^*Botanisches Institut der Universität München, Menzinger Strasse 67, D-8000 München 19
^†Institut für Physikalische Chemie der Technischen Universität München, Lichtenbergstrasse 4, D-8046 Garching, Federal Republic of Germany

Abstract

Chromopeptides were prepared by proteolytic digestion of phytochrome (far-red absorbing form, P_fr) and of phycocyanin. The phycocyanobilin peptide, the chromophore of which is Z,Z,Z-configurated, was modified to the Z,Z,E isomeric chromophore. It has been demonstrated earlier that the P_fr chromopeptide and the Z,Z,E-configurated phycocyanin chromopeptide behave similarly with regard to spectral and chromatographic properties and reactivity. We present evidence here, obtained by high-resolution ¹H NMR spectroscopy, that both the modified phycocyanobilin chromophore and the phytochrome chromophore obtained directly from P_fr are 15E-configurated.