Nitrogenase Enzyme Structure and Function скачать в хорошем качестве

Nitrogenase Enzyme Structure and Function

Nitrogenase Enzyme Structure and Function The nitrogenase enzyme occurs as three separate forms that use Mo, Fe-only, or V. The majority of global nitrogen fixation is attributed to the more efficient ‘canonical’ Mo-nitrogenase, whereas Fe-only and V-(‘alternative’) nitrogenases are often considered ‘backup’ enzymes, used when Mo is limiting. Nitrogenase is made of two component catalytic proteins: an electron donor (called the Fe protein) and electron acceptor component (the MoFe protein). The component proteins assemble in the presence of ATP bound to Fe protein, transfer electrons, and then dissociate. This cycle is repeated multiple times to achieve N2 reduction. The first crystal structures for the nitrogenase proteins (MoFe protein and Fe protein) were published in 1992 for the Azotobacter vinelandii. The core of each of catalytic components is formed by a NifD2K2 heterotetramer of approximately 230–240 kDa, arranged around a two fold symmetry axis. The two subunits are the 55 kDa NifD and the 53 kDa NifK. The D and K subunits are further structured into three globular domains with a canonical βαβ-fold, where a four- or five-stranded parallel β-sheet is flanked by connecting α-helices. #nitrogenaseenzyme #nitrogenfixation #nitrogengas #nitrogenasecomplex