Purification and Characterization of Soybean Root Nodule Ferric Leghemoglobin Reductase

Authors

Lin Ji, University of Nebraska - Lincoln
Stephen Wood, University of Nebraska-Lincoln
Manuel Becana, University of Nebraska-Lincoln
Robert V. Klucas, University of Nebraska - Lincoln

Date of this Version

1991

Citation

Plant Physiol. (1991) 96, 32-37

Comments

Copyright American Society of Plant Biologists. Used by permission.

Abstract

A ferric leghemoglobin reductase from the cytosol of soybean (Glyclne max) root nodules was purified to homogeneity and partlafly characterized. The enzyme is a flavoprotein with flavin adenine dinuclotide as the prosthetic group and consists of two identical subunits, each having a molecular mass of 54 kilodaltons. The pure enzyme shows a high activity for ferric leghemoglobin reduction with NADH as the reductant in the absence of any exogenous mediators. The enzyme also exhibits NADH-dependent 2,6-dichloroindophenol reductase activity. A sequence of the first 50 N-terminal amino acids of the purified protein was obtained. Comparisons with known protein sequences have shown that the sequence of the ferric leghemoglobin reductase is highly related to those of the flavin-nucleotide disulfide oxidoreductases, especially dihydrolipoamide dehydrogenase of the pyruvate dehydrogenase complex.