scholarly journals The activity of the dinuclear cobalt-β-lactamase from Bacillus cereus in catalysing the hydrolysis of β-lactams

2006 ◽  
Vol 401 (1) ◽  
pp. 197-203 ◽  
Author(s):  
Adriana Badarau ◽  
Christian Damblon ◽  
Michael I. Page
Keyword(s):  
Catalytic Activity ◽  
Bacillus Cereus ◽  
Metal Ion ◽  
Active Form ◽  
Metal Ion Binding ◽  
Deprotonated Form ◽  
Efficient Catalyst ◽  
Zinc Enzymes ◽  
Hydrolysis Of

Metallo-β-lactamases are native zinc enzymes that catalyse the hydrolysis of β-lactam antibiotics, but are also able to function with cobalt(II) and require one or two metal-ions for catalytic activity. The hydrolysis of cefoxitin, cephaloridine and benzylpenicillin catalysed by CoBcII (cobalt-substituted β-lactamase from Bacillus cereus) has been studied at different pHs and metal-ion concentrations. An enzyme group of pKa 6.52±0.1 is found to be required in its deprotonated form for metal-ion binding and catalysis. The species that results from the loss of one cobalt ion from the enzyme has no significant catalytic activity and is thought to be the mononuclear CoBcII. It appears that dinuclear CoBcII is the active form of the enzyme necessary for turnover, while the mononuclear CoBcII is only involved in substrate binding. The cobalt-substituted enzyme is a more efficient catalyst than the native enzyme for the hydrolysis of some β-lactam antibiotics suggesting that the role of the metal-ion is predominantly to provide the nucleophilic hydroxide, rather than to act as a Lewis acid to polarize the carbonyl group and stabilize the oxyanion tetrahedral intermediate.

scholarly journals The role of metal ion binding in the antioxidant mechanisms of reduced and oxidized glutathione in metal-mediated oxidative DNA damage

Metallomics ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Elias O. U. Eteshola ◽  
Devin A. Haupt ◽  
Stephen I. Koos ◽  
Lee A. Siemer ◽  
Daniel L. Morris
Keyword(s):  
Dna Damage ◽  
Metal Ion ◽  
Oxidative Dna Damage ◽  
Ion Binding ◽  
Oxidized Glutathione ◽  
Metal Ion Binding ◽  
Reduced And Oxidized Glutathione ◽  
Antioxidant Mechanisms

GSH and GSSG appear to function as antioxidants against metal-mediated oxidative DNA damage by coordinating Fe(ii) and Cu(ii).

Efficient Hydrolytic Breakage of β-1,4-Glycosidic Bond Catalyzed by a Difunctional Magnetic Nanocatalyst

2018 ◽  
Vol 71 (8) ◽  
pp. 559 ◽  
Author(s):  
Ren-Qiang Yang ◽  
Ni Zhang ◽  
Xiang-Guang Meng ◽  
Xiao-Hong Liao ◽  
Lu Li ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Time ◽  
Microcrystalline Cellulose ◽  
Significant Loss ◽  
Reducing Sugar ◽  
Magnetic Nanocatalyst ◽  
Efficient Catalyst ◽  
Glycosidic Bonds ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

A novel difunctional magnetic nanocatalyst (DMNC) was prepared and used to catalyse the hydrolytic breakage of β-1,4-glycosidic bonds. The functional nanoparticle displayed excellent catalytic activity for hydrolysis of cellobiose to glucose under moderate conditions. The conversion of cellobiose and yield of glucose could reach 95.3 and 91.1 %, respectively, for a reaction time of 6 h at pH 4.0 and 130°C. DMNC was also an efficient catalyst for the hydrolysis of cellulose: 53.9 % microcrystalline cellulose was hydrolyzed, and 45.7 % reducing sugar was obtained at pH 4.0 and 130°C after 10 h. The magnetic catalyst could be recycled and reused five times without significant loss of catalytic activity.

Towards the role of metal ions in the structural variability of proteins: CdII speciation of a metal ion binding loop motif

Metallomics ◽  
2011 ◽  
Vol 3 (12) ◽  
pp. 1331 ◽  
Author(s):  
Attila Jancsó ◽  
Dániel Szunyogh ◽  
Flemming H. Larsen ◽  
Peter W. Thulstrup ◽  
Niels Johan Christensen ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Structural Variability ◽  
Binding Loop

Complex Formation between [(η6-p-cymene)Ru(H2O)3]2+and Hydroxycarboxylates or their Sulfur Analogues - The Role of Thiolate Groups in Metal Ion Binding

2014 ◽  
Vol 2014 (30) ◽  
pp. 5204-5216 ◽  
Author(s):  
Dániel Hüse ◽  
Linda Bíró ◽  
János Patalenszki ◽  
Attila Csaba Bényei ◽  
Péter Buglyó
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding

scholarly journals A thiono-β-lactam substrate for the β-lactamase II of Bacillus cereus. Evidence for direct interaction between the essential metal ion and substrate

1989 ◽  
Vol 258 (3) ◽  
pp. 765-768 ◽  
Author(s):  
B P Murphy ◽  
R F Pratt
Keyword(s):  
Bacillus Cereus ◽  
Active Site ◽  
Metal Ion ◽  
Direct Interaction ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Enzyme Active Site ◽  
Lactam Carbonyl ◽  
Beta Lactamase Ii ◽  
Hydrolysis Of

An 8-thionocephalosporin was shown to be a substrate of the beta-lactamase II of Bacillus cereus, a zinc metalloenzyme. Although it is a poorer substrate, as judged by the Kcat./Km parameter, than the corresponding 8-oxocephalosporin, the discrimination against sulphur decreased when the bivalent metal ion in the enzyme active site was varied in the order Mn2+ (the manganese enzyme catalysed the hydrolysis of the oxo compound but not that of the thiono compound), Zn2+, Co2+ and Cd2+. This result is taken as evidence for kinetically significant direct contact between the active-site metal ion of beta-lactamase II and the beta-lactam carbonyl heteroatom. No evidence was obtained, however, for accumulation of an intermediate with such co-ordination present.

Role of the Surface-Exposed Leucine 155 in the Metal Ion Binding Loop of the CuA Domain of CytochromecOxidase fromThermus thermophiluson the Function and Stability of the Protein

Biochemistry ◽  
2012 ◽  
Vol 51 (12) ◽  
pp. 2443-2452 ◽  
Author(s):  
Manas Kumar Ghosh ◽  
Jitumani Rajbongshi ◽  
Debajani Basumatary ◽  
Shyamalava Mazumdar
Keyword(s):  
Metal Ion ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Binding Loop

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.

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