Comparative kinetics of Mg2+,Mn2+,Co2+, and Ni2+-activated glyoxalase I. Evaluation of the role of the metal ion

Biochemistry ◽  
1977 ◽  
Vol 16 (25) ◽  
pp. 5478-5484 ◽  
Author(s):  
Liang-Po B. Han ◽  
Christina M. Schimandle ◽  
Linda M. Davison ◽  
David L. Vander Jagt
Keyword(s):  
Metal Ion ◽  
Glyoxalase I ◽  
Kinetics Of

scholarly journals Evolutionary Expansion of the Amidohydrolase Superfamily in Bacteria in Response to the Synthetic Compounds Molinate and Diuron

2015 ◽  
Vol 81 (7) ◽  
pp. 2612-2624 ◽  
Author(s):  
Elena Sugrue ◽  
Nicholas J. Fraser ◽  
Davis H. Hopkins ◽  
Paul D. Carr ◽  
Jeevan L. Khurana ◽  
...  
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Active Sites ◽  
Evolutionary Transition ◽  
Functional Changes ◽  
Metal Ion Analysis ◽  
Amidohydrolase Superfamily ◽  
Kinetics Of ◽  
Hydrolysis Of

ABSTRACTThe amidohydrolase superfamily has remarkable functional diversity, with considerable structural and functional annotation of known sequences. In microbes, the recent evolution of several members of this family to catalyze the breakdown of environmental xenobiotics is not well understood. An evolutionary transition from binuclear to mononuclear metal ion coordination at the active sites of these enzymes could produce large functional changes such as those observed in nature, but there are few clear examples available to support this hypothesis. To investigate the role of binuclear-mononuclear active-site transitions in the evolution of new function in this superfamily, we have characterized two recently evolved enzymes that catalyze the hydrolysis of the synthetic herbicides molinate (MolA) and phenylurea (PuhB). In this work, the crystal structures, mutagenesis, metal ion analysis, and enzyme kinetics of both MolA and PuhB establish that these enzymes utilize a mononuclear active site. However, bioinformatics and structural comparisons reveal that the closest putative ancestor of these enzymes had a binuclear active site, indicating that a binuclear-mononuclear transition has occurred. These proteins may represent examples of evolution modifying the characteristics of existing catalysts to satisfy new requirements, specifically, metal ion rearrangement leading to large leaps in activity that would not otherwise be possible.

The Role of Metal Ion Solubility in Leaching of Nuclear Waste Glasses

1981 ◽  
Vol 11 ◽  
Author(s):  
B. Grambow
Keyword(s):  
Nuclear Waste ◽  
Metal Ion ◽  
Short Term ◽  
Long Term Performance ◽  
Term Performance ◽  
Kinetics Of ◽  
Elemental Release ◽  
Nuclear Waste Forms

The leachability of solid nuclear waste forms has been studied by many investigators to evaluate the short-term kinetics of elemental release or to determine the effects of leachant composition or other system parameters. Some general observations from these studies have included: incongruent leaching; formation of reaction layers that contain rare-earth, alkaline-earth, or transition metal elements; and apparent saturation of some elements in solution while others continue to be leached. Before these observations can be used to predict long-term performance of waste glasses under repository conditions, the mechanisms controlling the release of elements from the solid must be understood.

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

1993 ◽  
Vol 58 (5) ◽  
pp. 1001-1006 ◽  
Author(s):  
Oľga Vollárová ◽  
Ján Benko
Keyword(s):  
Transfer Functions ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Oxidation Of Co ◽  
Kinetics Of Oxidation ◽  
Tert Butyl ◽  
Tert Butyl Alcohol ◽  
Alcohol Mixtures ◽  
Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

Kinetics and mechanism of the reaction of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione

1990 ◽  
Vol 55 (8) ◽  
pp. 1984-1990 ◽  
Author(s):  
José M. Hernando ◽  
Olimpio Montero ◽  
Carlos Blanco
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics And Mechanism ◽  
Kinetic Constants ◽  
Steric Factors ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reactions of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione to form the corresponding monocomplexes have been studied spectrophotometrically in the range 5 °C to 16 °C at I 25 mol l-1 in aqueous solution. In the proposed mechanism for the two complexes, the enol form reacts with the metal ion by parallel acid-independent and inverse-acid paths. The kinetic constants for both pathways have been calculated at five temperatures. Activation parameters have also been calculated. The results are consistent with an associative activation for Fe(H2O)63+ and dissociative activation for Fe(H2O)5(OH)2+. The differences in the results for the complexes of heptanediones studied are interpreted in terms of steric factors.

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