Small-angle X-ray scattering studies on yeast inorganic pyrophosphatase and its interactions with divalent metal ions, inorganic phosphate, and hydroxymethane bisphosphonate |
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Authors: | P Thiyagarajan C S Borso A Banerjee B S Cooperman |
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Abstract: | Small-angle x-ray scattering studies have been carried out on the enzyme yeast inorganic pyrophosphatase (PPase), and its overall conformational changes on interaction with divalent metal ions (Mg2+ and Mn2+) and with phosphoryl ligands inorganic phosphate (Pi) and hydroxymethane bisphosphonate (PCHOHP), a nonhydrolyzable inorganic pyrophosphate analog] were assessed. The enzyme undergoes an apparent reduction in size on simultaneous addition of Mg2+ and high Pi concentration, although neithough neither Mg2+ nor Pi added separately induced any measurable conformational changes. By contrast, simultaneous addition of Mn2+ and Pi to PPase does not result in an observable conformational change. However, the overall structure of the enzyme appears to enlarge in the simultaneous presence of Mn2+ ions and PCHOHP. The significance of the structural changes seen in PPase under various conditions is discussed. |
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