661 



N. E. Tolbert 



the reactivity of excited FMN . Glycolate inhibition of the Hill 

 reaction when DCPIP is the oxidant (44), could be due to inhibi- 

 tion by the DCPIPH2 (45) produced from glycolate oxidation. High 

 O2 inhibits photosynthesis, but glycolate synthesis is favored 

 by high O2 pressure. Roux's data indicates that orthophosphate 

 or a phosphorylated compound may be an intermediate for O2 in 

 photosynthesis (46). The unexplained suppression of rapid gly- 

 colate labeling by phosphate or phosphoglycolate may be related 

 to some such phosphate requirement. Glycolate synthesis and me- 

 tabolism only during photosynthesis in a high O2 atmosphere, sug- 

 gest that its metabolism may be necessary to maintain in a reduced 

 state some auto oxidizable component of the chloroplast. 



Supported by NSF grant G24036 and published with approval of 

 the Director of the Michigan Agricultural Experiment Station. 



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