1nv3
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Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and Thallium (100 mM)
OverviewOverview
Fructose-1,6-bisphosphatase requires divalent cations (Mg2+, Mn2+, or, Zn2+) for catalysis, but a diverse set of monovalent cations (K+, Tl+, Rb+, or NH(4)(+)) will further enhance enzyme activity. Here, the, interaction of Tl+ with fructose-1,6-bisphosphatase is explored under, conditions that support catalysis. On the basis of initial velocity, kinetics, Tl+ enhances catalysis by 20% with a K(a) of 1.3 mm and a Hill, coefficient near unity. Crystal structures of enzyme complexes with Mg2+, Tl+, and reaction products, in which the concentration of Tl+ is 1 mm or, less, reveal Mg2+ at metal sites 1, 2, and 3 of the active site, but, little or no bound Tl+. Intermediate concentrations of Tl+ (5-20 mm), displace Mg2+ from site 3 and the 1-OH group of fructose 6-phosphate from, in-line geometry with respect to bound orthophosphate. Loop 52-72 appears, in a new conformational state, differing from its engaged conformation by, disorder in residues 61-69. Tl+ does not bind to metal sites 1 or 2 in the, presence of Mg2+, but does bind to four other sites with partial, occupancy. Two of four Tl+ sites probably represent alternative binding, sites for the site 3 catalytic Mg2+, whereas the other sites could play, roles in monovalent cation activation.
About this StructureAbout this Structure
1NV3 is a Single protein structure of sequence from Sus scrofa with F6P, MG, PO4 and TL as ligands. Active as Fructose-bisphosphatase, with EC number 3.1.3.11 Full crystallographic information is available from OCA.
ReferenceReference
Interaction of Tl+ with product complexes of fructose-1,6-bisphosphatase., Choe JY, Nelson SW, Fromm HJ, Honzatko RB, J Biol Chem. 2003 May 2;278(18):16008-14. Epub 2003 Feb 20. PMID:12595529
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