INVIVO TRANSFORMATION OF PHYCOBILIPROTEINS DURING PHOTOBLEACHING OF TOLYPOTHRIX-TENUIS TO FORMS ACTIVE IN PHOTOREVERSIBLE ABSORPTION CHANGES

The in vivo presence of the photoreversible pigment found by Scheibe was examined with T. tenuis before and after photobleaching. Crude protein extracts obtained from the cells before photobleaching showed no photoreversible absorption changes. Distinct photoreversible absorption changes were observed in crude protein extracts obtained from the cells after photobleaching. Photobleaching caused the formation of photoreversible pigment(s) in vivo. Fractionation by brushite column chromatography revealed that 2 photoreversible chromoproteins were present in the latter extracts. One was eluted at the same fraction as allophycocyanin and showed a green minus red difference spectrum identical with that of Scheibe''s photoreversible pigment, that of phycochrome c of Bjorn and Bjorn and that of our guanidine-HCl-treated allophycocyanin. The other chromoprotein was found in the phycocyanin fraction and showed a green minus red difference spectrum resembling that of our guanidine-HCl-treated phycocyanin and that of the phycochrome a of Bjorn and Bjorn. The photoreversible chromoproteins present in cells after photobleaching were transformed in vivo from phycobiliproteins during the treatment. Re-evaluation of the photobiological role of these chromoproteins is necessary.