Sulphite and nitrite reductases are vital in the biosynthetic assimilation of sulphur and nitrogen, respectfully. They are also both important for the dissimilation of oxidised anions for energy transduction.

1: Sulfite reductase structure at 1.6 A: evolution and catalysis for reduction of inorganic anions. Crane BR, Siegel LM, Getzoff ED; Science 1995;270:59-67. PMID:7569952

2: Probing the catalytic mechanism of sulfite reductase by X-ray crystallography: structures of the Escherichia coli hemoprotein in complex with substrates, inhibitors, intermediates, and products. Crane BR, Siegel LM, Getzoff ED; Biochemistry 1997;36:12120-12137. PMID:9315849