XVI International Botanical Congess

We used homology modeling to identify potential oxidizable Cys groups in four light-activated chloroplast enzymes. Our predictions were in agreement with the experimental results for glyceraldehyde-3-P dehydrogenase and fructose bisphosphatase, but another pair of Cys residues is responsible for sedoheptulose bisphosphatase activity modification. Although our experimental results with malate dehydrogenase are consistent with our model, the crystal structure (see abstracts, this session) reveals another disulfide. It seems likely that one of the Cys residues forms two different disulfide bonds. We have used modeling successfully as a tool in screening for additional redox-sensitive enzymes.