CARBON DIOXIDE FIXATION 295 



plasts. Then we will not have to worrjf about contamination from enzymes that 

 came from mitochondria. 



Krall : I have made a comparison of Dr. Arnon's published rates of C'^02 uptake 

 with the rate of photosynthetic Ci^02 fixation by barley leaves in 2% CO2. This 

 may not be a fair comparison because the barley leaf is a much more active system 

 than the spinach leaf. Using Arnon's highest value, the calculations show that 

 barley fixes C'^ at about 1000 times the rate of chloroplast preparations. 



M. B. Allen: With the reconstituted system we have obtained far higher rates 

 than that. 



Amon : I question the validity of Dr. Krall's comparison. 



References 



1. Arnon, D. I., Allen, M. B., and Whatley, F. R., Nature, 174, 394 (1954). 



2. Allen, M. B., Arnon, D. I., Capindale, J. B., Whatley, F. R., and Durham, L. 



J., J. Am. Chem. Soc, 77, 4149 (1955). 



3. Arnon, D. I., Allen, M. B., and Whatley, F. R., Biochim. et Biophys. Acta, 20, 



449 (1956). 



4. Whatley, F. R., Allen, M. B., Rosenberg, L. L., Capindale, J. B., and Arnon, 



D. I.^ Biochim. et Biophys. Acta, 20, 462 (1956). 



5. Fuller, R. C, Allen, AI. B., Whatley, F. R., and Arnon, D. I., unpublished data. 



6. Rosenberg, L. L., and Arnon, D. I., J. Biol. Chem., 217, 361 (1955). 



