Changes in hydrogen-bond strengths explain reduction potentials in 10 rubredoxin variants.

ABSTRACT: The rubredoxin from Clostridium pasteurianum (CpRd) provides an excellent system for investigating how the protein sequence modulates the reduction potential of the active site in an iron-sulfur protein. (15)N NMR spectroscopy has allowed us to determine with unprecedented accuracy the strengths of all six key hydrogen bonds between protein backbone amides and the sulfur atoms of the four cysteine residues that ligate the iron in the oxidized (Fe(III)) and reduced (Fe(II)) forms of wild-type CpRd and nine mutants (V44G, V44A, V44I, V44L, V8G, V8A, V8I, V8L, and V8G/V44G). The length (or strength) of each hydrogen bond was inferred from the magnitude of electron spin delocalized across the hydrogen bond from the iron atom onto the nitrogen. The aggregate lengths of these six hydrogen bonds

SUBMITTER: Lin IJ 

PROVIDER: S-EPMC1239895 | biostudies-literature | 2005 Oct

REPOSITORIES: biostudies-literature