XVI International Botanical Congess
The plant dihydrofolate reductase-thymidylate synthases are bifunctional enzymes that contain several cysteine residues. When we computationally substituted the cysteines in the carrot and Arabidopsis enzymes into the 3-dimensional structure of the Leishmania major enzyme we found potential disulfides in the reductase domains of both enzymes. Treatment of crude extracts with dithiothreitol orglutathione causes marked inhibition of reductase activity. These results suggest that the activity of this enzyme might be subject to redox-regulation in green plants. Supported by US NSF and DOE.