2.7.7.23 Ca2+ - 674815 2.7.7.23 Ca2+ 2 mM. Activation of UDP-N-acetylglucosamine diphosphorylase activity in the order of decreasing effectiveness: Mg2+, Zn2+, Ca2+, Co2+, Mn2+. No activity is detectable without a divalent cation 725308 2.7.7.23 Ca2+ activates 756049 2.7.7.23 Ca2+ Ca2+ shows similar enhancement like Mg2+ 674815 2.7.7.23 Ca2+ no activity is detectable when a divalent cation is removed from the reaction buffer. The order of effectiveness of metal ions on GlcNAc-1-P UTase activity is Mg2+ > Zn2+ > Ca2+ > Co2+ > Mn2+, which is different from that of its Glc-1-P TTase activity, Co2+ > Mn2+ > Mg2+ > Zn2+ > Ca2+ 748123 2.7.7.23 Co2+ 2 mM. Activation of UDP-N-acetylglucosamine diphosphorylase activity in the order of decreasing effectiveness: Mg2+, Zn2+, Ca2+, Co2+, Mn2+. No activity is detectable without a divalent cation 725308 2.7.7.23 Co2+ a cobalt ion substitutes for Mg2+A in the crystal structure 740866 2.7.7.23 Co2+ absolute requirement for a divalent cation. The order of effectiveness of metal ions on the activity of the enzyme is Co2+, Mn2+, Mg2+ and Zn2+ 748158 2.7.7.23 Co2+ binds to enzyme 643075 2.7.7.23 Co2+ can partially replace Mg2+ 643057, 643059, 643061, 643067 2.7.7.23 Co2+ can partially replace Mn2+ 643065 2.7.7.23 Co2+ no activity is detectable when a divalent cation is removed from the reaction buffer. The order of effectiveness of metal ions on GlcNAc-1-P UTase activity is Mg2+ > Zn2+ > Ca2+ > Co2+ > Mn2+, which is different from that of its Glc-1-P TTase activity, Co2+ > Mn2+ > Mg2+ > Zn2+ > Ca2+ 748123 2.7.7.23 Mg2+ - 674815, 706622 2.7.7.23 Mg2+ 2 mM. Activation of UDP-N-acetylglucosamine diphosphorylase activity in the order of decreasing effectiveness: Mg2+, Zn2+, Ca2+, Co2+, Mn2+. No activity is detectable without a divalent cation 725308 2.7.7.23 Mg2+ absolute requirement for a divalent cation. The order of effectiveness of metal ions on the activity of the enzyme is Co2+, Mn2+, Mg2+ and Zn2+. The optimal Mg2+ concentration is 6 mM, but the enzymatic activity does not change substantially between 2 and 12 mM 748158 2.7.7.23 Mg2+ absolutely required, optimal concentration 20 mM 718708 2.7.7.23 Mg2+ can partially replace Mn2+ 643065 2.7.7.23 Mg2+ cofactor 643076 2.7.7.23 Mg2+ highest activity when ratio Mg2+/diphosphate is 1/10 - 1/20 643060 2.7.7.23 Mg2+ in complex with UTP 662429 2.7.7.23 Mg2+ inhibitory at high concentrations 643059 2.7.7.23 Mg2+ Mg2+ enhances the enzymatic activity by increasing the affinity between UTP and the enzyme 674815 2.7.7.23 Mg2+ no activity is detectable when a divalent cation is removed from the reaction buffer. The order of effectiveness of metal ions on GlcNAc-1-P UTase activity is Mg2+ > Zn2+ > Ca2+ > Co2+ > Mn2+, which is different from that of its Glc-1-P TTase activity, Co2+ > Mn2+ > Mg2+ > Zn2+ > Ca2+ 748123 2.7.7.23 Mg2+ optimum activity at 3 mM 288685 2.7.7.23 Mg2+ or Mn2+, required 721526 2.7.7.23 Mg2+ required 720042, 729696, 735518, 735569, 736517, 737291, 737319, 740262, 741091, 741100, 755852, 756049, 760395, 761091, 761532 2.7.7.23 Mg2+ required for maximum activity 288685, 643057, 643058, 643059, 643060, 643061, 643067 2.7.7.23 Mg2+ required, the enzyme utilizes two metal ions, MgA 2+ and MgB 2+, to catalyze the uridyltransfer reaction. The enzyme binds three magnesium ions and ATP at the active site. Displacement of MgB2+ from its usual catalytically competent position, as noted in the crystal structure of RNA polymerase in an inactive state, is considered to be a key factor inhibiting the reaction. In GlmUMtb[GlcNAc-1-P:ATP], the third metal ion, MgC2+ is also stabilized by one coordination interaction with Palpha and five coordination interactions with water molecules. Its coordination by Palpha results in the stabilization of an inactive conformation of ATP. Structure-function analysis, overview. The entire metal-substrate complex renders the enzyme catalytically inactive 735396 2.7.7.23 Mg2+ required, two metal binding sites, site-A and site-B. The enzyme uses a two-metal ion mechanism (mechanism-B). Roles of the metal ions in substrate stabilization, nucleophile activation and transition-state stabilization, detailed overview. Mg2+A interacts with Asp114 and Asn239 and oxygens O1B and O2A of UDP-GlcNAc in addition to two water molecules. Mg2+B is coordinated with three water molecules and the oxygen atoms are contributed by UDP-GlcNAc and diphosphate. Mg2+A enables nucleophile activation and Mg2+B stabilizes the transition state 740866 2.7.7.23 Mg2+ strictly required. One magnesium ion catalyzes the sugar-nucleotidyl transfer reaction. 5 mM used in assay conditions 760506 2.7.7.23 Mg2+ strictly required. Two magnesium ions catalyze the sugar-nucleotidyl transfer reaction. 5 mM used in assay conditions 760506 2.7.7.23 Mn2+ 2 mM. Activation of UDP-N-acetylglucosamine diphosphorylase activity in the order of decreasing effectiveness: Mg2+, Zn2+, Ca2+, Co2+, Mn2+. No activity is detectable without a divalent cation 725308 2.7.7.23 Mn2+ absolute requirement for a divalent cation. The order of effectiveness of metal ions on the activity of the enzyme is Co2+, Mn2+, Mg2+ and Zn2+ 748158 2.7.7.23 Mn2+ activates 756049 2.7.7.23 Mn2+ can partially replace Mg2+ 643057, 643058, 643059, 643061, 643067 2.7.7.23 Mn2+ no activity is detectable when a divalent cation is removed from the reaction buffer. The order of effectiveness of metal ions on GlcNAc-1-P UTase activity is Mg2+ > Zn2+ > Ca2+ > Co2+ > Mn2+, which is different from that of its Glc-1-P TTase activity, Co2+ > Mn2+ > Mg2+ > Zn2+ > Ca2+ 748123 2.7.7.23 Mn2+ or Mg2+, required 721526 2.7.7.23 Mn2+ or Mg2+, required. At 5 mM, 126% of the activity with Mg2+ 721526 2.7.7.23 Mn2+ required for maximum activity, 0.5-1 mM 643065 2.7.7.23 additional information the three-dimensional structure of the ST0452 mutant Y97N is not changed by due to lack of metals but the interactions with the substrate is slightly modified, which might cause the activity to increase 760395 2.7.7.23 Ni2+ can partially replace Mn2+ 643065, 643067 2.7.7.23 Ni2+ inhibitory 643057 2.7.7.23 Zn2+ - 674815 2.7.7.23 Zn2+ 2 mM. Activation of UDP-N-acetylglucosamine diphosphorylase activity in the order of decreasing effectiveness: Mg2+, Zn2+, Ca2+, Co2+, Mn2+. No activity is detectable without a divalent cation 725308 2.7.7.23 Zn2+ absolute requirement for a divalent cation. The order of effectiveness of metal ions on the activity of the enzyme is Co2+, Mn2+, Mg2+ and Zn2+ 748158 2.7.7.23 Zn2+ no activity is detectable when a divalent cation is removed from the reaction buffer. The order of effectiveness of metal ions on GlcNAc-1-P UTase activity is Mg2+ > Zn2+ > Ca2+ > Co2+ > Mn2+, which is different from that of its Glc-1-P TTase activity, Co2+ > Mn2+ > Mg2+ > Zn2+ > Ca2+ 748123 2.7.7.23 Zn2+ Zn2+ shows similar enhancement like Mg2+ 674815