Rubredoxin from a Nitrogen‐Fixing Variety of Desulfovibrio desulfuricans

Abstract
Rubredoxin from Desulfovibrio desulfuricans var. azotovorans, with a molecular weight of 6,500 ± 60, has an amino acid composition different from those of other rubredoxins. Ultraviolet, optical rotatory dispersion and circular dichroism spectra indicate chemical similarities to other rubredoxins: including stability to guanidine denaturation, relative inaccessibility of the chromophoric iron to cyanide and certain chelating agents. The presence of four –SH groups, relatively inaccessible to –SH reagents, and one Fe per molecule, the latter in an environment of low asymmetry when reduced, is consistent with a structure proposed by Bachmayer et al. in 1968 for the rubredoxin of Micrococcus aerogenes.