146 



METABOLISM AND PHYSIOLOGY 

 TABLE 4 



Effects of 'hmconplers" on light-stimulated oxidation of H2 ivith fiimarate 

 and photophosphorylation by R. ruhrum. particles* 



Inhibitor 



(M) 



Particle Cone. 



(mg bacterio- 



chl./3 ml) 



Activity 

 ■Photohydro- Photophos- 

 genase" phorylation 



(% of eontrol) 



After Bose (62). Particles were prepared as described in ref. 47 and illumi- 

 nated with red light. Reaction mixtures (in Warburg vessels) contained, in a 

 final volume of 3 ml: particles, as indicated; Tris-HCl pH 7.9, 200 /imoles; 

 TMPD, 2 /Umoles; sodium fumarate, 40 fimoles; ADP, 2 /ymoles; K2HPO4, 40 

 //moles; MgCl2, 30 //moles; hexokinase, 1 mg; mannose, 60 //moles. Gas phase, 

 H2 (KOH in center well); temperature, 30°C. The particles were preincubated 

 with inhibitors for approximately 10 minutes and the extent of phosphorylation 

 determined in the usual way after deproteinization of the suspensions used for 

 the manometric assays. 



donors to acceptors) and cyclic photophosphorylation, A number of 

 studies (47,49,65-68) indicate that electrons from substrates such as 

 NADH2, succinate, and H2 can eventually interact with carriers of the 

 photophosphorylating chain. It is possible that such interconnections 

 are merely concerned with maintaining the latter carriers in states of 

 optimal redox balance, but further investigation is required to estab- 

 lish their true import. 



