2eip
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INORGANIC PYROPHOSPHATASE
OverviewOverview
The refined crystal structures of hexameric soluble inorganic, pyrophosphatase from E. coli (E-PPase) are reported to R factors of 18.7, and 18.3% at 2.15 and 2.2 A, respectively. The first contains one, independent monomer; the other, two independent monomers, in an R32 unit, cell. Because the E-PPase monomer is small with a large open active site, there are relatively few hydrophobic interactions that connect the, active-site loops to the five-stranded twisted beta-barrel that is the, hydrophobic core of the molecule. The active-site loops are, however, held, in place by interactions between monomers around the threefold and twofold, symmetry axes of the D(3) hexamer. Consequently, mutations of active-site, residues (such as Glu20 and Lysl04) often affect protein stability and, oligomeric structure. Conversely, mutations of residues in the interface, between monomers (such as His136 and Hisl40) not only affect oligomeric, structure but also affect active-site function. The effects of the H136Q, and H140Q variants can be explained by the extended ionic interaction, between H140, D143 and H136' of the neighbouring monomer. This interaction, is further buttressed by an extensive hydrogen-bonding network that, appears to explain why the E-PPase hexamer is so stable and also why the, H136Q and H140Q variant proteins are less stable as hexamers.
About this StructureAbout this Structure
2EIP is a Single protein structure of sequence from Escherichia coli. This structure superseeds the now removed PDB entry 1EIP. Active as Inorganic diphosphatase, with EC number 3.6.1.1 Full crystallographic information is available from OCA.
ReferenceReference
Structure of Escherichia coli inorganic pyrophosphatase at 2.2 A resolution., Kankare J, Salminen T, Lahti R, Cooperman BS, Baykov AA, Goldman A, Acta Crystallogr D Biol Crystallogr. 1996 May 1;52(Pt 3):551-63. PMID:15299678
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