Nitrogenase Iron-Molybdenum Cofactor Binding Site: Protein Conformational Changes Associated with Cofactor Binding

Abstract

Formation of active nitrogenase MoFe-protein requires the assembly and insertion of a unique molybdenum containing Fe:S cluster, the FeMoco. The protein acceptor is held in an open conformation by the binding of a small molecular weight protein, γ. Using selective alkylation of the protein cysteines, conformational changes associated with γ binding and cofactor insertion were evaluated and a model for the change presented. Reversible oxygen damage to the precursor is identified and evaluated in terms of the chemistry of dithionite used in the buffer as an oxygen scavenger.

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