Magnesium trifluoride, MgF₃^-, has been assigned [1, 2] and under-assigned [3] as the molecular species seen in x-ray structures of trigonal-bipyramidal species (tbp) of enzymes catalysing phosphoryl transfer. A structure of ß-phosphoglucomutase (ßPGM) complexed with G6P has been presented as a pentacovalent tbp phosphorus intermediate [3]. Our alternative attribution of MgF₃^- as the tbp species [4] has been strongly rejected [5].

Kinetic, spectroscopic, and structural data confirms MgF₃^- as a TSA for ßPGM. F^- is a strong inhibitor for ßPGM and 19F NMR analysis shows three F^- ions are recruited into the active site of the enzyme in the presence of G6P. NOE analysis using 15N,2H-labelled ßPGM shows 4 amino acids in close contact with two F^-; the third F^- is co-ordinated to a catalytic Mg₂⁺ ion. This accurately locates the binding site for MgF₃^- which is further co-ordinated to G6P C1-OH group and to Asp8. In examples of metal fluoride complexes of phosphoryl transfer enzymes identified by x-ray analysis, the presence of F^- (rather than OH^-) must be inferential at the resolutions achieved. Our results constitute the first direct observation of a metal fluoride complex as a TSA for a phosphoryl transfer enzyme. The bonding in the tbp accurately portrays the transition state for phosphoryl transfer in ßPGM and reveals the details of protein catalysis.

[1] D. L. Graham, P. N. Lowe et al., Chem. Biol. 2002, 9, 375-381.
[2] M. F. Bowler, G. M. Blackburn, A. G. W. Leslie, J. E. Walker, Abstr. Gordon Conf. Biophys. 2005.
[3] S. D. Lahiri, G. Zhang, D. Dunaway-Mariano et al., Science (Washington, DC, USA) 2003, 299, 2067-2071.
[4] G. M. Blackburn, N. H. Williams et. al., Science (Washington, DC, USA) 2003, 301, 1184.
[5] L. W. Tremblay, G. Zhang et al., J. Am. Chem. Soc. 2005, 127, 5298-5299.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8092 must be provided.