The structural basis for pyrophosphatase catalysis

: Heikinheimo P, Lehtonen J, Baykov A, Lahti R, Cooperman BS, Goldman A

Publisher: CURRENT BIOLOGY LTD

: 1996

: Structure

: STRUCTURE

: 4

: 12

: 1491

: 1508

: 18

: 0969-2126

DOI: https://doi.org/10.1016/S0969-2126(96)00155-4(external)

Conclusions: Our structure-based model of the PPase mechanism posits that the nucleophile is the hydroxide ion mentioned above. This aspect of the mechanism is formally analogous to the 'two-metal ion' mechanism of alkaline phosphatase, exonucleases and polymerases. A third metal ion coordinates another water molecule that is probably the required general acid. Extensive Lewis acid coordination and hydrogen bonds provide charge shielding of the electrophile and lower the pK(a) of the leaving group. This 'three-metal ion' mechanism is in detail different from that of other phosphoryl transfer enzymes, presumably reflecting how ancient the reaction is.