1908 



KINETICS OF PHOTOSYNTHESIS 



CHAP. 37D 



about equally strong (the rate was reduced to one half by about 3 X 10~^ 

 m./l. NaF); no evidence was found of the accumulation of oxidizable 

 intermediates in light (as in fig. 37D.8B). 



Hydroxylamine. Gaffron, Fager and Rosenberg (1951) reported that 

 adding 6 X 10 ~^ M hydroxylamine to photosynthesizing *Sce7ierfeswMS two 

 minutes before darkening and C(14)-tagging, inhibits the post-illumination 



no lAA ^x 



270 1- 



Fig. 37D.8B. Enhanced O2 consumption following in- 

 hibition of photosynthesis in Chlorella by iodoacetic acid 

 (lAA) (after Holzer 1954). 30° C, other conditions as in 

 fig. 37D.8A. 



C*-fixation by about 40%; Avhile 3 X 10"^ M NH2OH, added together 

 with the tracer in the dark, have no effect. This is in agreement with the 

 assumption that NH2OH (in contrast to HON), does not act on the pri- 

 mary carboxylation reaction, but affects the accumulation of the carbon 

 dioxide-acceptor in light. 



Calvin ei at. (1951) found that given during active photosynthesis, 5 X 

 10-^ M NH2OH— which inhibits the rate of photosynthesis by 75%— af- 

 fects more strongly the C*-fixation in sugar phosphates (after one minute 

 exposure to C*02 in light) less strongly that in PGA, and least of all, that 

 in mahc acid. The fixation in glutamic, succinic, fumaric and citric acid 



