| MECHANISM OF ACTION |
NITROGENASE catalyzes the redn of N2 to NH3 & is the key enzyme in BIOLOGICAL NITROGEN fixation. The MoFe protein of nitrogenase contains a Fe-Mo cofactor that is the site of N coordination & redn. Researchers have shown that this complex cofactor – which is buried 10 angstroem beneath the protein’s surface – is assembled outside the MoFe protein, but exactly how the cofactor is then delivered & inserted has remained a mystery. Researchers have shed some light on how this cofactor is incorporated by solving the X-ray crystal structure of the Fe-Mo protein from “Azotobacter vinelandii” to 2.3-angstroem resolution. The researchers isolated cofactor- deficient protein from cells lacking one of the proteins required for biosyn thesis of a precursor to the cofactor. Unlike the holoprotein [Nature, 360, p. 553 (1992)], the cofactor-deficient protein has a positively charged funnel from the protein’s surface to the cofactor binding site through which the negatively charged cofactor is inserted. The authors note that residue rearran gements near the funnel’s opening may facilitate docking of the protein that delivers the cofactor |
| UPDATE | 04.02 |
| AUTHOR | This data is not available for free |
| LITERATURE REF. | This data is not available for free |
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