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Electrochemical Characterization of Isolated Nitrogenase Cofactors from Azotobacter vinelandii
Author(s) -
Lydon Brian R.,
Lee Chi Chung,
Tanifuji Kazuki,
Sickerman Nathaniel S.,
Newcomb Megan P.,
Hu Yilin,
Ribbe Markus W.,
Yang Jenny Y.
Publication year - 2020
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201900425
Subject(s) - cofactor , nitrogenase , azotobacter vinelandii , chemistry , redox , molybdenum , molybdenum cofactor , stereochemistry , biochemistry , enzyme , inorganic chemistry , organic chemistry , nitrogen fixation , nitrogen
The nitrogenase cofactors are structurally and functionally unique in biological chemistry. Despite a substantial amount of spectroscopic characterization of protein‐bound and isolated nitrogenase cofactors, electrochemical characterization of these cofactors and their related species is far from complete. Herein we present voltammetric studies of three isolated nitrogenase cofactor species: the iron–molybdenum cofactor (M‐cluster), iron–vanadium cofactor (V‐cluster), and a homologue to the iron–iron cofactor (L‐cluster). We observe two reductive events in the redox profiles of all three cofactors. Of the three, the V‐cluster is the most reducing. The reduction potentials of the isolated cofactors are significantly more negative than previously measured values within the molybdenum–iron and vanadium–iron proteins. The outcome of this study provides insight into the importance of the heterometal identity, the overall ligation of the cluster, and the impact of the protein scaffolds on the overall electronic structures of the cofactors.