THE PROTEIN-CHLOROPHYLL-770 COMPLEX FROM 

 GREEN BACTERIA 



JOHN M. OLSON, DAVID FILMER, ROGER RADLOFF, 



CAROL A. ROMANO, and CHRISTIAAN SYBESMA 



Biology Department, Brookhaven National Laboratory, 



Upton, Neiv York 



Last year a protein- chlorophyll complex was extracted from two 

 species of green bacteria and separated from the predominant pigment, 

 chlorobium chlorophyll (1). The chlorophyll of the complex was named 

 chlorophyll-770 because of the position of the main absorption band in 

 ether. The spectral resemblance to bacteriochlorophyll was note- 

 worthy. The general occurrence of chlorophyll-770 in all green bac- 

 teria is suggested by the absorption spectra of cell suspensions and 

 extracts obtained by various workers (1-3) with different strains. The 

 function of chlorophyll-770 as an acceptor of electronic excitation 

 energy from chlorobium chlorophyll has recently been demonstrated 

 (4), and its ability to sensitize the light-driven oxidation of cytochrome 

 in vivo is described elsewhere in this volume (5), In the present 

 paper the following properties of the protein- chlorophyll- 770 complex 

 from Chloropseudomonas ethylicum, strain 2K, are given: absorption 

 spectra, fluorescence emission spectra, sedimentation coefficient, 

 molecular weight, magnesium content, and nitrogen content. 



PREPARATION OF MATERIAL 



Protein- chlorophyll preparations were obtained from both Cps. 

 ethylicum 2K and Chlorobium thiosulfatophilum, strain L, by the pro- 

 cedure shown in Fig, 1, Bacteria were ruptured either by freezing and 

 thawing or by means of a French pressure cell. The eluate from the 

 DEAE-cellulose could be further purified by readsorption ontoDEAE- 

 cellulose followed by gradient elution with NaCl in 0,02 M phosphate 

 buffer, pH = 7,8, Preparations sufficiently pure for quantitative char- 

 acterization have so far been obtained from Cps. ethylicum only. 



Extraction of the chlorophyll-770 from the complex was accom- 

 plished by precipitating the complex with (NH4)2S04, 30 per cent 

 (W/V), and homogenizing the precipitate in 80 per cent methanol at 

 40°C, The chlorophyll-770 was transferred to ether (1) and chroma- 



423 



