ISOLATED CHLOROPLASTS 



121 



Speculation is likely to be profitable, but it may well be that 

 a correct interpretation of the induction phase in photosyn- 

 thesis might provide a guiding principle for the setting up 

 of biochemical models of photosynthesis in vitro. 



TABLE 7.1 



STANDARD OXIDATION-REDUCTION POTENTIALS 



(a) Biological substances 



The following table lists the standard oxidation reduction 

 potential Eq at pH 7-0 and at 25° C. referred to the standard 

 hydrogen electrode. It also gives the standard free energy (AFq) 

 for reduction in the reaction A+H2 -* AH2 per hydrogen atom or 

 electron transferred and the free energy (AFq') for the reaction 

 A+H2O -^ AH2+i02 (i.e. referred to a theoretical standard oxygen 

 electrode). The relation between AFq and Eq is 

 AFo=-23,o68n(£'o'+o-o6 pH) 

 in which n has been taken as unity. 



* Average value based on the free energy of the reaction 

 iCsHijO.+Oa -* C02+H20,AFo' + 1 15,000 cals. 



(b) Other chloroplast reactants 



