The long term goals are to elucidate the structure and biology of this enzyme and start studies on the 5'-nucleosidase and possible xanthine transporters in root nodules. Mark Hargrove and John Olson at Rice University, Texas. The goals are to structurally characterize these proteins, attempt to obtain co-crystals of the reductase and its substrate, leghemoglobin and understand the regulation of the reductase in the different tissues of soybean. Towards these ends, we have cloned and overexpressed leghemoglobins and two different reductase genes. The leaf form of the reductase has been purified recently, and we are in the process of biochemically characterizing this isoform.
Initial data indicate several difference from the root nodule isoform.
Our studies on plant hemoglobins have used soybean leghemoglobin as a model for the symbiotic forms and rice hemoglobins as the model for the nonsymbiotic forms. All of these proteins have been over-expressed and purified.