Protein Conformation; Pyrococcus horikoshii/enzymology; Pyrophosphatases/chemistry; Pyrophosphatases/metabolism; Amino Acid Sequence; Base Sequence; Binding Sites; Cations, Divalent/metabolism; Conserved Sequence; Crystallography, X-Ray; Dimerization; Escherichia coli/genetics; Hydrogen Bonding; Hydrolysis; Inosine Monophosphate/metabolism; Ligands; Light; Manganese/metabolism; Models, Chemical; Models, Molecular; Molecular Sequence Data; Plasmids; Protein Binding; Protein Folding; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Structure, Tertiary; Pyrococcus horikoshii/chemistry; Pyrophosphatases/genetics; Recombinant Proteins/chemistry; Recombinant Proteins/metabolism; Rotation; Scattering, Radiation; Sequence Homology, Amino Acid; Synchrotrons; Transformation, Bacterial; Water/chemistry; X-Ray Diffraction; Inosine Triphosphatase