[Todos] Seminario INQUIMAE-DQIAFQ_Miércoles 2 de Diciembre, 13hs

[Mireille Perec]

Seminarios INQUIMAE-DQIAQF


 

Miércoles 2 de Diciembre 13 hs.

Aula Seminarios INQUIMAE-DQIAQF

Ciudad Universitaria Pab. II 3° Piso

Professor Gerhard Schenk

School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Qld 4072, Australia

 


GpdQ, an Enzymatic Bioremediator with an Interesting Mechanism of Action




The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di- and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents.  GpdQ has attracted recent attention as a promising enzymatic bioremediator.  In the absence of substrates the enzyme exists predominantly in a catalytically inactive mononuclear state.  The addition of substrate increases the affinity of the second metal binding site (the â site), leading to the formation of an active binuclear catalyst.  Stopped-flow fluorescence measurements identified three distinct phases in the catalytic turnover, associated with the (i) initial binding of substrate to the active site, (ii) the assembly of a catalytically active binuclear centre, and (iii) subsequent slower structural rearrangements to optimize catalysis. Furthermore, the hydrogen bond network that connects the substrate binding pocket with the two metal ions plays an important role in modulating both the coordination of the â metal ion and the mechanism of catalysis.  The latter is associated with the flexible coordination of one of the ligands to the weaker bound â metal ion (Asn80).  Overall, GpdQ employs an intricate regulatory mechanism for catalysis, a paradigm of a substrate- and metal ion-induced fit to optimize catalysis.

 

 References:

      Hadler K.S., Gahan L.R., Ollis D.L. and Schenk G. (2009) The bioremediator glycerophosphodiesterase employs a non-processive mechanism for hydrolysis. J. Inorg. Biochem. (in press).

      Hadler K.S., Mitic N., Ely F., Hanson G.R., Gahan L.R., Larrabee J.A., Ollis D.L. and Schenk G. (2009) Structural flexibility enhances the reactivity of the bioremediator glycerophosphodiesterase by fine-tuning its mechanism of hydrolysis. J. Am. Chem. Soc. 131: 11900-11908.
     
      Hadler K.S., Tanifum E.A., Yip S., Mitic N., Guddat L.W., Jackson C.J., Gahan L.R., Nguyen K., Carr P.D., Ollis D.L., Hengge A.C., Larrabee J.A. and Schenk G. (2008) Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in glycerophosphodiesterase from Enterobacter aerogenes. J. Am. Chem. Soc. 130: 14129-14138.
     

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