Phytochromes are red/far-red photoreceptors and ubiquitous in the animal and plant kingdom (Nature 407:585). Although their universal action as light- sensing devices in organisms and their ability to respond optimally to environmental changes is known (Genes & Dev. 14:257), the mechanism on the molecular level is still an area of intensive investigations. This powerful attribute has its origin in a linear tetrapyrrole (bilin) prosthetic group which is covalently bound to the apo-protein via a cysteine thioether linkage (Figure 1).  We are building up conceptualized oligopyrroles with restricted conformational flexibility in order to reassemble the holo-phytochrome in its active/inactive form. We intend to build up C,D ring components with  locked configurations/conformations by introducing appropriate substituents (R) in the periphery (Figure 2). To synthesize substituted dipyrrinones we plan to apply various reaction types like transition metal catalysis, cyclisation reactions and Barton-Zard Pyrrole Syntheses.

Figure 1

Figure 2