Is Mo involved in hydride binding by the four-electron reduced (E4) intermediate of the nitrogenase MoFe protein?

ABSTRACT: We here report the first direct evidence addressing the possible involvement of Mo in substrate interactions during catalytic turnover. When the alpha-70(Ile) MoFe protein is freeze-trapped during H(+) reduction under Ar, the majority of the resting state EPR signal from the molybdenum-iron cofactor (FeMo-co) disappears and is replaced by the S = 1/2 signal of an intermediate that has been shown to be the E(4) MoFe state, which is activated for N(2) binding and reduction through the accumulation of 4 electrons/protons by FeMo-co. ENDOR studies of E(4) showed that it contains two hydrides bound to FeMo-co. We calculate that Mo involvement in hydride binding would require a vector-coupling coefficient for Mo of |K(Mo)| approximately > 0.2 and determine K(Mo) for the E(4) intermediate state t

SUBMITTER: Lukoyanov D 

PROVIDER: S-EPMC2828500 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature