681 



C. P. Whittingham, et al. 



Ihese data are consistent with light production of 2-carbon compounds from 

 glucose which may be subsequently metabolised via serine to give either amino 

 acids, e.g., alanine and aspartate, or sugars, e.g., sucrose, according to the 

 experimental conditions. 



Evidence for the latter pathway was found when serine-3--^^C was fed to 

 Chlorella in the presence of 0.03% CO2 and 99.97%, the principal end products 

 being sucrose and glycollate. In an attempt to trap a possible intermediate, 

 e.g., PGA, iodo-acetamide was added at 5 x 10"^ M, but this had the surprising 

 effect of increasing the rate of conversion of serine to all canpounds. 



d) Use of specifically labelled substrates 



Further experiments of the type just described were made using radioactive 

 glucose specifically labelled in only one carbon atom. The radioactive 



