655 



N. E. Tolbert 



Photosynthetic Requirements For Glycolate Synthesis 



Light and effect of CMU and Cl-CCP : Very high light intensi- 

 ties are required for maximum glycolate synthesis and excretion 

 (5, 26, 29). When Chlorella were grown continuously in fluores- 

 cent red light they incorporated little C^'* into glycolate during 

 10 min. exposure to C^'*02 in either red or white light, but they 

 still labeled glycine and serine (Table 1). They acted like Mn 

 deficient algae. When Chlorella were grown in blue light, much 

 of the C^"* was fixed into glycolate and it was excreted. Note 

 also that algae grown in red light labeled aspartate but not when 

 grown in blue light. Cayle and Emerson (36) have also reported 

 greater C^^ specific activity in glycine and serine during photo- 

 synthesis in blue light. 



Table 1. Influence of red and blue light on C^^^Os fixation. 



% Distribution of C^"* 



^Nearly similar results were obtained with Chlorella. 

 ^'''"Almost entirely aspartic, glutamic and malic. 



CMU inhibits O2 production during photosynthesis. As indicated 

 in Table 2, the synthesis of glycolate products, phosphate esters 

 of the carbon cycle and sucrose were reduced proportionally by CMU. 

 However, with CMU a much greater percent of the fixed C^'^ appeared 

 in glutamic, aspartate and malate. In comparison Cl-CCP, which 

 inhibits photophosphorylation, preferentially reduced C^"* labeling 

 of aspartate, glutamate and malate. CMU and Cl-CCP did not inhibit 

 glycolate phosphatase in vitro. 



