Site-directed mutagenesis FeMoco

In addition, site-directed mutagenesis has been used to probe cluster binding, and extrusion studies of FeMoco centers and P clusters have provided a considerable insight to their structures. 

When FeMoco extracted from MoFe protein purified from a nifV mutant is recombined with apo-MoFe protein, the activated protein has the substrate-reducing characteristics of the nifV enzyme (reduces C2H2 effectively but N2 only poorly). This observation provides the most compelling evidence that FeMoco is, or forms part of, the active site of nitrogenase. Site-directed mutagenesis has implicated one of the conserved Cys residues of the a subunit Cys 275 in binding FeMoco, and also His 196 and Gin 192 (see Refs. 17 and 38 for discussion). 

Recently, site-directed mutagenesis studieshave shown that cysteine residues are involved in binding FeMoco to the subunits of [FeMo]. Moreover, these studies again implicate FeMoco in the substrate-reducing site. 

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