116 THE BACTERIAL PHOTOCHEMICAL APPARATUS 



364 



0.5 



794 



880 



-Absorption spectrum of "normal", washed chromatophores 



Fig. 1. 



from R. ruhrum in 0.1 M K giycylglycine pH 7.7. 



Absorption spectrum of B794 particles (obtained from 2-day-old 



cultures) after removal of 880 m/i absorbing material by differential centrifu- 

 gation; in 0.1 M K giycylglycine pH 7.7. 



believe this to be an extraction artifact since bacteriopheophytin does 

 not form readily from bacteriochlorophyll even in the presence of dilute 

 acids, and the isolation procedures have been carried out under con- 

 ditions which should prevent the accumulation of acids in the extrac- 

 tion mixtures. 



The cause for the discrepancy in the position of the in situ absorp- 

 tion peaks near 800 m^ in the two types of particles may be ascribed 

 to the presence or absence of the BgSO bacteriochlorophyll. The BssQ 

 material has a higher extinction at 800 vafj. than at 794 m/i; thus, in 

 the presence of excess B88O the absorption peak of the presumed 

 bacteriopheophytin would tend to be shifted toward longer wavelengths 

 {i.e., from 794 m^ toward 800 m/i). A more quantitative evaluation of 

 this spectral shift will be attempted. 



