Author/Editor		Baxter, Nikola J; Olguin, Luis F; Goličnik, Marko; Feng, Guoqiang; Hounslow, Andrea M; Bermel, Wolfgang; Blackburn, Michael G; Hollfelder, Florian; Waltho, Jonathan P; Williams, Nicholas H
Title		A Trojan horse transition state analogue generated by MgF3 formation in an enzyme active site
Type		članek
Source		PNAS
Vol. and No.		Letnik 103, št. 40
Publication year		2006
Volume		str. 14732-7
Language		eng
Abstract		Identifying how enzymes stabilize high-energy species along the reaction pathway is central to explaining their enormous rate acceleration. Beta-Phosphoglucomutase catalyses the isomerization of beta-glucose-1-phosphate to beta-glucose-6-phosphate and appeared to be unique in its ability to stabilize a high-energy pentacoordinate phosphorane intermediate sufficiently to be directly observable in the enzyme active site. Using 19F-NMR and kinetic analysis, we report that the complex that forms is not the postulated high-energy reaction intermediate, but a deceptively similar transition state analogue in which MgF3- mimics the transferring P03- moiety. Here we present a detailed characterization of the metal ion-fluoride complex bound to the enzyme active site in solution, which reveals the molecular mechanism for fluoride inhibition of beta-phosphoglucomutase. This NMR methodology has a general application in identifying specific interactions between fluoride complexes and proteins and resolving structural assignments that are indistinguishable by x-ray crystallography.
Descriptors		PHOSPHOGLUCOMUTASE GLUCOSE-6-PHOSPHATE KINETICS BINDING SITES FLUORIDES PHOSPHORYLATION MAGNETIC RESONANCE IMAGING