Approaches to a reaction mechanism for soybean ferric leghemoglobin reductase.

摘要

A protein with ferric leghemoglobin reductase (FLbR) activity was isolated and purified from soybean nodules. The gene encoding FLbR was cloned, sequenced and the recombinant FLbR was expressed in Escherichia coli. In this dissertation the sequence and size of the cloned insert DNA were determined to confirm that the recombinant DNA is FLbR gene. Western blot analysis of the protein and the kinetic properties (;The enzymatic activities and kinetic properties were compared with dihydrolipoamide dehydrogenases (DHLipDHs). FLbR has multiple activities but it has the highest affinity and specificity for the ferric state of leghemoglobin (Lb). The evidence supports the postulation that FLbR functions to reduce the ferric state of Lb. FLbR has a disulfide group in the active site of the enzyme and a two-electron transfer dominates in the reduction of the ferric state of Lb as shown by the inhibition of FLbR activity by disulfide-binding compounds. The mid-point potential (E