Comparison of main emissions at—196°C from phycobilisomes of two blue-green algaeAnabaena cylindricaandAnacystis nidulans

摘要

Main emissions at—196°C from phycobilisomes of two blue-green algaeAnabaena cylindricaandAnacystis nidulanswere studied with special reference to allophycocyanin (APC) B content. Supplementary experiments were done withAnabaena variabilis(M-2 and M-3). The main emission from phycobilisome ofAnacystis nidulansrich in APC B was located at 681 nm. The location was identical to that of the main emission from APC B but at a shorter wavelength than that of in vivo emission (685 nm). Results indicate that APC B acts as the energy output of phycobilisomes, but that the in vivo 685 nm emission is not attributed to APC B.The main emission of the phycobilisome ofAnabaena cylindricawas always located at 685 nm irrespective of the preparation method; 0.75 M phosphate buffer [Plant Physiol., 63: 615–620 (1979)] or 30%polyethylene glycol [Special Issue of Plant&Cell Physiol., No. 3, p. 23–31 (1977)]. This alga also contained a special form of APC, but its content was very low. The location of its emission band (681 nm) was identical to that of APC B, but shorter than that of the main band of phycobilisomes (685 nm). The 685 nm emitter in phycobilisomes showed a character similar to chlorophyllabut not phycobiliproteins in treatments for aqueous extraction or methanol extraction. Results indicate that the pigment is probably chlorophyllaas we assumed previously. The 685 nm emission from phycobilisomes ofAnabaena variabilis(M-2 and M-3) showed the same character.Results were interpreted as indicating that (i) the content of the special form of APC varies with the species or strain of blue-green algae and (ii) the energy at the phycobilin level is transferred directly from APC to pigment system II chlorophyllawhen the amount of the special form of APC