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RADIATION BIOLOGY 



(Fig. 5-3a, h). A very large shift upon extraction is also found in the 

 absorption maximum of the green pigment of green sulfur bacteria (Fig. 

 5-4). The absorption maxima in the red and near-infrared regions of 

 aqueous colored extracts from ground cells of either green plants or the 

 photosynthetic bacteria are at practically the same positions as in the 



O 



8000 9000 



WAVE LENGTH, A 



7000 



8000 

 WAVE LENGTH, A 



8100 



(a) (b) 



Fig. 5-3. (a) Infrared absorption spectra (of bacteriochloroiihyll-protein complexes) 

 of some purple bacteria, measured in the living cells. (1) Chromutium, strain D; (2) 

 Rhodospir ilium rubrum, strain 1; (3) Rhodovibrio, strain 1. {From Wassink, 1942; 

 data from Wassink et al., 1939.) 



(b) Infrared absorption spectra of extracted bacteriochlorophyll from some purple 

 bacteria (in ethanol). (1) Chromatium, strain D; (2) Rhodospirillum rubrum, strain 

 1; (3) Rhodovibrio, strain 1; (4) Phaeomonas varians, strain 4. (From Wassink, 1942; 

 data from Wassink et al., 1939.) 



6400 



7000 

 WAVE LENGTH, A 



8000 8400 



Fig. 5-4. Infrared absorption maximum of green bacteria (bacterioviridin) (upper 

 curve), and its shift upon ethanol extraction (lower curve). {From Wassink, 1942, 

 according to Katz and Wassink, 1939.) 



living cells (Fig. 5-5a, h). The pigmented material does not precipitate 

 with moderate centrifugal force. Electrophoretic movement is shown in 

 an electric field, which movement at a certain pH is reversed (Katz 

 and Wassink, 1939). In aging cultures of purple bacteria a colored mate- 

 rial sometimes extrudes from the cells and remains suspended in the 

 nutrient medium. Its absorption spectrum is quite similar to that of 

 the living cells and to that of the extracts obtained by grinding. 



