682 





C. P. Vftiitt Ingham, et al. 



glycollate produced was degraded and the percentage activity In each of the two 

 carbon atoms determined following the method given by Aronoff(12). 



The results show that C^ of glucose gives rlSe to C2 of glycollate and C2 of 

 glucose to Cl of glycollate. Also if Cg labelled glucose is supplied, the 

 results are essentially the same as when C^ Is fed. Varying oxygen or carbon 

 dioxide partial pressure did not affect these results despite the large changes 

 induced in the production of glycollate. Production of Cp labelled glycollate 

 from the Ci of glucose would be consistent with the occurrence of a transketo- 

 lase reaction involving, e.g., fructose-6-P, and the subsequent liberation of 

 glycollate from a 2-carbon thiamine-pyrophosphate intermediate as has been 

 shown in vltro ^^^^. However, it is difficult to equate the roles of light and 

 CO2 with such a mechanism in vivo . 



ACKNaVLEDGEfCNTS 



This research was supported in v\rfiole or in part by the United States Air 

 Force under Grant No. AP-EOAR 62-24 and monitored by the European Office of 

 Aerospace Research. R. G. H. is an I.C.I, fellow of the University of London. 



REFERENCES 



(1) Bassham, J. A., and Calvin, M. (1957). The Path of Carbon in Photosyn- 

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(2) Whittin^am, C. P., and Pritchard, G. G. (1963). Proc. Roy. Soc. B. 157, 

 366. 



(3) Wilson, A. T., and Calvin, M. (1955). J. Am. Chem. Soc. 77, 5948. 



(4) Tblbert, N. E., and Zill, L. P. (1956). J. Biol. Chem. 222, 895. 



(5) Calkins, V. P. (1943). Ind. Eng. Chem. Anal. Ed. 15, 7627" 



