2nac
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(New page: 200px<br /><applet load="2nac" size="450" color="white" frame="true" align="right" spinBox="true" caption="2nac, resolution 1.80Å" /> '''HIGH RESOLUTION STRU...)
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Revision as of 10:39, 21 November 2007
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HIGH RESOLUTION STRUCTURES OF HOLO AND APO FORMATE DEHYDROGENASE
Overview
Three-dimensional crystal structures of holo (ternary complex, enzyme-NAD-azide) and apo NAD-dependent dimeric formate dehydrogenase, (FDH) from the methylotrophic bacterium Pseudomonas sp. 101 have been, refined to R factors of 11.7% and 14.8% at 2.05 and 1.80 A resolution, respectively. The estimated root-mean-square error in atomic co-ordinates, is 0.11 A for holo and 0.18 A for apo. X-ray data were collected from, single crystals using an imaging plate scanner and synchrotron radiation., In both crystal forms there is a dimer in the asymmetric unit. Both, structures show essentially 2-fold molecular symmetry. NAD binding causes, movement of the catalytic domain and ordering of the C terminus, where a, new helix appears. This completes formation of the enzyme active centre in, holo FDH. NAD is bound in the cleft separating the domains and mainly, interacts with residues from the co-enzyme binding domain. In apo FDH, these residues are held in essentially the same conformation by water, molecules occupying the NAD binding region. An azide molecule is located, near the point of catalysis, the C4 atom of the nicotinamide moiety of, NAD, and overlaps with the proposed formate binding site. There is an, extensive channel running from the active site to the protein surface and, this is supposed to be used by substrate to reach the active centre after, NAD has already bound. The structure of the active site and a hypothetical, catalytic mechanism are discussed. Sequence homology of FDH with other, NAD-dependent formate dehydrogenases and some D-specific dehydrogenases is, discussed on the basis of the FDH three-dimensional structure.
About this Structure
2NAC is a Single protein structure of sequence from Pseudomonas sp. with SO4 as ligand. Active as Formate dehydrogenase, with EC number 1.2.1.2 Full crystallographic information is available from OCA.
Reference
High resolution structures of holo and apo formate dehydrogenase., Lamzin VS, Dauter Z, Popov VO, Harutyunyan EH, Wilson KS, J Mol Biol. 1994 Feb 25;236(3):759-85. PMID:8114093
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