PHOTOSYNTHETIC PHOSPHORYLATION AND THE ENERGY CONVTIRSION PROCESS 383 



TABLE XII 



Hydrogen Evolution from Reduced Methyl Violo(;en by Cell- Free 

 Hydrogenase FROM Chrotnotiuni 



(Ogata, Nozaki, and Arnon, [91]) 



/(moles Ho evolved/ 

 10 min./mg. chl. 



Complete system 

 Methyl viologen omitted 

 Na2S,04 omitted 

 Hydrogenase omitted 



12-8 



none 

 none 

 none 



Complete systeni contained, in a final volume of 3-0 ml., cell-free suspension 

 (PS) containing 0-4 mg. bacteriochlorophyll and 80 /nmoles tris buffer, pH 7-2. 

 o-i ml. of 20",, KOH was present in the centre well and 16 ^imoles of methyl 

 viologen was added to the sidearm. Methyl viologen was reduced by adding Na.2S.2O4 

 to the same sidearm while gassing with argon. The reaction was carried out at 30" 

 in the dark. 



reactions as in the reduction of CO.^ via pyridine nucleotides or in the 

 photofixation of N.,. 



The hydrogenase present in ChromoUuui particles that catalyzes 

 hydrogen evolution in the light can also catalyze hydrogen gas evolution 



text. 



LIGHT 



Non-cyclic electron transport in Chromatium 

 Fig. 24. Scheme for non-cyclic electron flow in Chroniatiian. Details in the 



in the dark (Table XII) when electrons are supplied at a sufficiently 

 reducing potential, as for example by hydrosulphite (cf. [132]). Methyl 

 viologen was required as a catalyst in this reaction (compare [156, 1^7]). 



