A Novel Chromophore Selectively Modifies the Spectral Properties of One of the Two Stable States of the Plant Photoreceptor Phytochrome

Abstract

An efficient synthetic access to phytochromobilin (1), the chromophore of the plant photoreceptor phytochrome, and to its constitutional isomer “iso”-phytochromobilin (2) is reported. Both tetrapyrroles are assembled spontaneously with a recombinant apoprotein to form photochemically functional phytochromes. Interestingly, in the case of 2 the absorption maximum of the physiologically active phytochrome state selectively undergoes a hypsochromic shift (Pfr; fr=far red).