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| [[Image:1nv0.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1nv0| PDB=1nv0 | SCENE= }} | | {{STRUCTURE_1nv0| PDB=1nv0 | SCENE= }} |
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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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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12595529}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12595529 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12595529}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Gluconeogenesis]] | | [[Category: Gluconeogenesis]] |
| [[Category: Hydrolase]] | | [[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 Sun Jul 27 21:23:38 2008'' |