In vivo transformation of phycobiliproteins during photobleaching ofTolypothrix tenuisto forms active in photoreversible absorption changes

摘要

The in vivo presence of the photoreversible pigment found by Scheibe was examined withTolypothrix tenuisbefore and after photobleaching. Crude protein extracts obtained from the cells before photobleaching showed no photoreversible absorption changes. However, distinct photoreversible absorption changes were observed in crude protein extracts obtained from the cells after photobleaching. Results indicate that photobleaching caused the formation of photoreversible pigment(s) in vivo. Fractionation by brushite column chromatography revealed that two 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 (5), that of phycochrome c of Björn and Björn (2), and that of our guanidine-HCl-treated allophycocyanin (7). 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 (7) and that of the phycochrome a of Björn and Björn (2). Results indicate that 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 necess