Different effects of Mg2+ and Zn2+ on the two sites for alkylammonium compounds in Pseudomonas aeruginosa phosphorylcholine phosphatase

OTERO, LH; BEASSONI, PR; BOETSCH, C; LISA, AT; DOMENECH, CE

Enzyme Research

SAGE-Hindawi

Lugar: Londres; Año: 2011 vol. 2011 p. 1 - 7

2090-0414

Pseudomonas aeruginosa phosphorylcholine phosphatase (PchP) catalyzes the hydrolysis of phosphorylcholine (Pcho), is activated by Mg2+ or Zn2+, and is inhibited by high concentrations of substrate. This study has shown that PchP contains two sites for alkylammonium compounds (AACs): one in the catalytic site near the metal ion-phosphoester pocket, and the other in an inhibitory site responsible for the binding of the alkylammonium moiety. The catalytic mechanism for the entry of Pcho in both sites and Zn2+ or Mg2+ follows a random sequential mechanism. However, Zn2+ is more effective than Mg2+ at alleviating the inhibition produced by the entry of Pcho or different AACs in the inhibitory site.We postulate that Zn2+ induces a conformational change in the active center that is communicated to the inhibitory site, producing a compact or closed structure. In contrast,Mg2+ produces a relaxed or open conformation.