172 



PROBLEMS OF PHOTOSYNTHESIS 



aerobically dissociating CO-2, i.e., the CO2 which is bound under the influence 

 of O2 only. Table 22 and Figure 66 show the results of these subtractions. 



TABLE 22 



Dissociating CO2, anaerobically and aerobically 



It follows from Figure 66 that, both anaerobically and aerobically, the degree 

 of saturation is reached at a CO2 pressure of 50 vol %. The degree of satu- 

 ration is about 2.5 times greater for aerobically dissociating CO2 than for 

 anaerobically dissociating CO2. 



40 50 



volume % CO? 



Fig. 66. Evolution of dissociating COo from Chlorella with '/so A' NaF. pH 3.8, 20° C. 

 Curve I: anaerobically dissociating COi. Curve H: only aerobically dissociating CO2 

 (Warburg et al., Zschr. Naturf.). 



Curve II for aerobically dissociating CO2 is strongly dependent upon the 

 method of Chlorella cultivation. Cells cultivated with fluctuating light (A- 

 cells) give the best quantum yields and bind COo aerobically much more 

 strongly than south cells which give poor quantum yields (see § 15). It is 

 also of interest to note that the saturation value for aerobically dissociating 

 COo is equal to the glutamic acid content of the cells. In the experiment 

 shown in Figure 66, the latter was 38.4 ix\ and the saturation value for aero- 

 bically dissociating COo was 41 jjX. As the chlorophyll content was 41.2 /xl, 

 it follows that, within the limits of experimental error, chlorophyll content, 

 glutamic acid content and aerobically dissociating CO2 are identical. 



