1nv2
Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and Thallium (20 mM)Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and Thallium (20 mM)
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFructose-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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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