View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Research Article 1491 The structural basis for pyrophosphatase catalysis Pirkko Heikinheimo1,2, Jukka Lehtonen1,2, Alexander Baykov3, Reijo Lahti2, Barry S Cooperman4* and Adrian Goldman1,2* Background: Soluble inorganic pyrophosphatase (PPase), an essential Addresses: 1Turku Centre for Biotechnology, PO enzyme central to phosphorus metabolism, catalyzes the hydrolysis of the phos- Box 123, FIN-20521 Turku, Finland, 2Department phoanhydride bond in inorganic pyrophosphate. Catalysis requires divalent of Biochemistry, University of Turku, FIN-20014 Turku, Finland, 3A.N. Belozersky Institute of metal ions which affect the apparent pKas of the essential general acid and Physico-Chemical Biology, Moscow State base on the enzyme, and the pKa of the substrate. Three to five metal ions are University, Moscow 119899, Russia and required for maximal activity, depending on pH and enzyme source. A detailed 4Department of Chemistry, University of understanding of catalysis would aid both in understanding the nature of biolog- Pennsylvania, Philadelphia, PA 19104, USA. ical mechanisms of phosphoryl transfer, and in understanding the role of diva- *Corresponding authors. lent cations. Without a high-resolution complex structure such a model has E-mail:
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[email protected] Key words: mechanism, phosphoanhydride Results: We report the first two high-resolution structures of yeast PPase, at hydrolysis, phosphoryl transfer, pyrophosphatase, 2.2 and 2.0 Å resolution with R factors of around 17 %. One structure contains refinement, structure the two activating metal ions; the other, the product (MnPi)2 as well.