Metal Systems for Group Transferases and Their Models

Dinuclear Metal Systems for Group Transferases and Their Models 

Peptidase and Phosphatase Enzymes with Multinuclear Metal Complex 

The two-metal mechanisms have been known for most phosphotransferases e.g., alkaline phosphatase (7), inositol monophosphatase 

The X-ray crystal structure of the inorganic phosphate (an inhibitor) complex of alkaline phosphatase from E. coli (9) showed that the active center consists of a Zn2Mg(or Zn) assembly, where the two zinc(II) atoms are 3.94 A apart and bridged by the bidentate phosphate (which suggests a phosphomonoester substrate potentially interacting with two zinc(II), as depicted in Fig. 2), and the Mg (or the third Zn) is linked to one atom of the zinc pair by an aspartate residue at a distance 

Although the detailed catalytic mechanisms of these phosphatases have not been elucidated, an accepted general mechanism is that the two metal ions are cooperatively working by interacting directly with the scissible phosphate and stabilizing the pentacovalent intermediate (33, 45). Moreover, one zinc(II) ion generates the attacking OH ion. 

The two-metal mechanisms have been known for most phosphotransferases e.g., alkaline phosphatase (7), inositol monophosphatase (35), serine/threonine phosphatase-1 (36), and purple acid phosphatase (30). The catalytic function of the metals in these multinuclear metallo-enzymes may be rather electrostatic and seems insensitive to the nature of the metal ions. 

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