168 



PROBLEMS OF PHOTOSYNTHESIS 



Steady state is reached, the suspension is centrifuged, the cells are again sus- 

 pended in 3 ml water and heated to 90° C for 5 min. The liquid is centri- 

 fuged again, dried in vacuo and examined. The chromatograms show the 

 presence of aspartic acid, glutamic acid, alanine and 7-aminobutyric acid. 

 There are no variations in the concentrations of aspartic acid and alanine. 

 Table 20 shows the expected changes, which have already been discussed, 

 with regard to glutamic acid and 7-aminobutyric acid. 



The experiments with lyophilized cells and those using paper chromatog- 

 raphy clearly show that the labile CO2 of Chlorella developed when NaF is 

 added or when other measures are applied originates from decarboxylation 

 of glutamic acid. By adding NaF to living cells we are able to elicit the 

 breakdown and resynthesis of glutamic acid in life and to study the function 

 of this amino-acid in living Chlorella. 



TABLE 20 

 Results of chromatography studies 



It follows from Table 20 that noteworthy differences exist between high and 

 low NaF concentrations. The concentration Vso N is very high and de- 

 composes glutamic acid irreversibly, under anaerobic and aerobic conditions. 

 With low concentrations (Viooo to V 300 N NaF) glutamic acid is reversibly 

 decomposed and respiration is increased. Thus, it is not possible to deter- 

 mine the presence of glutamic acid by means of manometric pressure changes 

 when low NaF concentrations are used under aerobic conditions. To meas- 

 ure aerobic glutamic acid breakdown manometrically, Warburg (13) uses 

 initially a low concentration of NaF and afterwards a high concentration. 

 If, for instance, 40 m1 CO2 are directly produced aerobically with Vso N 

 NaF and only 30 m1 CO2 when previously Viooo N NaF had been given, it 

 may be concluded that the low NaF concentration decomposed 25% of the 

 glutamic acid. 



