28o MARTIN D. KAMEN 



TABLE I 



Molecular Composition of Chromatium Chromatophores 



(after Newton and Newton [ii]) 



Based on i gm. wet weight of washed chromatophores 



Protein (nig.) 



Cytochrome (/um) 



Carbohydrate (mg.) 

 Acid-soluble 

 Insoluble 



Lipid (mg.) 



Pigtnents (i-im) 



Bacterio-chlorophyll 

 Bacterio-carotenoid 



Nucleotides (/^tivi) 

 Pyridine 



Flavin (/xm) 



Phosphorus (/xm) 

 Acid-soluble 



Insoluble 



Iron (imM) 



Acid-soluble 



1 66 (modified biuret reaction) 



o- 18 (determined as pyridine hemochromogen) 



62 



5 



57 



87 



3-4 

 I -6 



9-5 

 02 



o- 17 



85 

 9-4 



73 



12 

 5 



(anthrone reaction) 

 (mostly pentose) 

 (galactose polymer) 



(mostly phospholipid ; only base detected- 

 ethanolaniine) 



(spectrophotometric assay) 

 (spectrophotometric assay) 



(based on u.v. absorption as adenine) 

 (fluorimeter assay of TCA extract) 



(8-5 /uM of this fraction accounted for as 



inorganic P) 

 (51 /tM of this fraction accounted for as lipid P) 



(mostly non-haem) 



(mostly present in ferrous form) 



tenoids [16, 17], the haem proteins [18, 19] and the quinones [12]. The 

 major finding appears to be that the bacterial chromatophores are relatively 

 rich in RNA [14] and depleted in DNA [14], which suggests a basic 

 composition like that of microsomes, as regards gross composition. In 

 fact, the overall P distribution in various fractions of silver beet micro- 

 somes, as obtained by Martin and Morton [20], are much like those found 

 by Newton and Newton [11] for Chrumatium chromatophores. Results 

 given by Nakamura, Chow, and Vennesland [21] for spinach chloroplast 

 preparations also do not differ significantly from those reported for the 

 chromatophores. The relation of nucleic acids to development of photo- 

 active structures remains to be elucidated. A beginning has been made by 

 Brawerman and Chargoff [5] whose interesting work I can only mention 

 in passing because of time limitations. It is noteworthy, as far as photo- 

 chemical function is concerned, that Nakamura et ah [21] reported 

 extensive enzymic depolymerization of nucleic acid in chloroplast frag- 

 ments failed to impair the photophosphorylation capacity. This indicates 



