704 



LIGHT ABSORPTION V,Y PIGMENTS 7.V VIVO 



f'HAP. 22 



Table 22.V 



Absorption Maxima of Purplk Bacteria (after Wassink, 

 Katz and Dorrestein 1939) 



m/i 



854 



S50 . 5 



SoG" 



852.5 



865 1 



858 / 



Species and strain -~ 



Thwrhodaceae 

 Strain D (Roelefson) 895 



Strains 1 , 4, 7,12 (v:ui \i<-l) 895 



Strains 9, b, 19 (van Niel-AIuller) 895 



Strains 101, 201 Weak 



Si mill, ;!01, 401 895 



AOtiorltoddceae 



Rhoduvibrio (2 strains) 865 — 



864 — 



Rhodohadllus palustn's (3 strains) 881 ] 



873 [ — 



862. 5j 



Phaeonwnas varians (Streptococcus varians) (3 



strains) 885 1 



885 [ 850 . 5 



892.5] 



Rhodospir ilium rvhrum (2 strains) 875 \ 



878 / 



III 



803.5 

 79f) 

 796 

 803.5 



802.5 

 803 



802 



r799 

 799 



(798.5 



800 



complexes in the individual species and strains. The complexes may be 

 formed by combination of the same pigment (bacteriochlorophyll) with 

 different proteins, each complex being perhaps specifically adapted to the 

 utilization of one reductant, such as hydrogen, sulfide, thiosulfate or an or- 

 ganic hydrogen donor (this hypothesis was suggested by Wassink, Katz and 

 Dorrestein). Other possibilities include several isomeric or tautomeric 

 forms of bacteriochlorophyll, or small differences in chemical composition, 

 or in the reduction level, of the pigment. 



If this interpretation of the three cell bands is correct, the question 

 arises as to the reasons for the absence in live cells of a counteipart to the 

 605 mp solution band of bacteriochlorophyll. No answer can be given to 

 this question — except that the matter requires renewed, and more syste- 

 matic, investigation. It was mentioned in chapter 21 (page 618) that the 

 role of the 605 niM band is not quite clear even in solution spectra. 



According to Katz and Wassink (1939), live green sulfur bacteria have 

 two absorption maxima (at 740 and 810 m^, respectively) instead of the 

 single band found in bacterioviridin extracts (at 668 m^, cf. fig. 22.28). 

 According to the statement on page 642 the width of the "red shift" is in 

 agreement with the hypothesis that bacterioviridin is a derivative of tetra- 

 hydroporphin (as assumed on page 445 in Vol. I). 



