Soybean dihydrolipoamide dehydrogenase (ferric leghemoglobin reductase 2) interacts with and reduces ferric rice non-symbiotic hemoglobin 1.

Ferrous oxygenated hemoglobins (Hb²⁺O₂) autoxidize to ferric Hb³⁺, but Hb³⁺ is reduced to Hb²⁺ by enzymatic and non-enzymatic mechanisms. We characterized the interaction between the soybean ferric leghemoglobin reductase 2 (FLbR2) and ferric rice non-symbiotic Hb1 (Hb1³⁺). Spectroscopic analysis showed that FLbR2 reduces Hb1³⁺. Analysis by tryptophan fluorescence quenching showed that FLbR2 interacts with Hb1³⁺, however the use of ITC and IEF techniques revealed that this interaction is weak. In silico modeling showed that predicted FLbR2 and native Hb1³⁺ interact at the FAD-binding domain of FLbR2 and the CD-loop and helix F of Hb1³⁺.