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'''Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and 1 mM Thallium''' | '''Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and 1 mM Thallium''' | ||
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[[Category: Honzatko, R B.]] | [[Category: Honzatko, R B.]] | ||
[[Category: Iancu, C V.]] | [[Category: Iancu, C V.]] | ||
[[Category: | [[Category: Allosteric enzyme]] | ||
[[Category: | [[Category: Bisphosphatase]] | ||
[[Category: | [[Category: Gluconeogenesis]] | ||
[[Category: | [[Category: Hydrolase]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:00:48 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 03:00, 3 May 2008
Fructose-1,6-Bisphosphatase Complex with Magnesium, Fructose-6-Phosphate, Phosphate and 1 mM Thallium
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
1NV0 is a Single protein structure of sequence from Sus scrofa. 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 Page seeded by OCA on Sat May 3 03:00:48 2008