scholarly journals Ligand interactions at the active site of aspartate transcarbamoylase from Escherichia coli

Biochemistry ◽  
1986 ◽  
Vol 25 (7) ◽  
pp. 1605-1611 ◽  
Author(s):  
Paul R. Dennis ◽  
M. Vijaya Krishna ◽  
Maria Di Gregorio ◽  
William W. C. Chan
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Aspartate Transcarbamoylase ◽  
Ligand Interactions

scholarly journals Hydroxo-Bridged Active Site of Flavodiiron NO Reductase Revealed by Spectroscopy and Computations

2020 ◽  
Author(s):  
Filipe Folgosa ◽  
Vladimir Pelmenschikov ◽  
Matthias Keck ◽  
Christian Lorent ◽  
Yoshitaka Yoda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Density Functional Theory ◽  
Data Collection ◽  
Active Site ◽  
Density Functional ◽  
Nuclear Resonance ◽  
Structural Studies ◽  
Functional Theory ◽  
Nuclear Resonance Vibrational Spectroscopy ◽  
Ligand Interactions

<p>NO and O<sub>2</sub> are detoxified in many organisms using flavodiiron proteins (FDPs). The exact coordination of the iron centre in the active site of these enzymes remains unclear despite numerous structural studies. Here, we used <sup>57</sup>Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the iron-ligand interactions in <i>Escherichia coli</i> FDP. This data combined with density functional theory (DFT) and <sup>57</sup>Fe Mössbauer spectroscopy indicate that the oxidised form of FDP contains a dihydroxo-diferric Fe(III)–(µOH<sup>–</sup>)<sub>2</sub>–Fe(III) active site, while its reduction gives rise to a monohydroxo-diferrous Fe(II)–(µOH<sup>–</sup>)–Fe(II) site upon elimination of one bridging OH<sup>–</sup> ligand, thereby providing an open coordination site for NO binding. Prolonged NRVS data collection of the oxidised FDP resulted in photoreduction and formation of a partially reduced diiron center with two bridging hydroxyl ligands. These results have crucial implications for studying and understanding the mechanism of FDP as well as other non-haem diiron enzymes.</p>

scholarly journals Arginine 54 in the active site of escherichia coli aspartate transcarbamoylase is critical for catalysis: A site-specific mutagenesis, NMR, and X-ray crystallographic study

1992 ◽  
Vol 1 (11) ◽  
pp. 1435-1446 ◽  
Author(s):  
Jeffrey W. Stebbins ◽  
Diane E. Robertson ◽  
Mary F. Roberts ◽  
Raymond C. Stevens ◽  
William N. Lipscomb ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Aspartate Transcarbamoylase ◽  
Site Specific ◽  
X Ray ◽  
Crystallographic Study ◽  
A Site

scholarly journals Hydroxo-Bridged Active Site of Flavodiiron NO Reductase Revealed by Spectroscopy and Computations

2020 ◽  
Author(s):  
Filipe Folgosa ◽  
Vladimir Pelmenschikov ◽  
Matthias Keck ◽  
Christian Lorent ◽  
Yoshitaka Yoda ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Density Functional Theory ◽  
Data Collection ◽  
Active Site ◽  
Density Functional ◽  
Nuclear Resonance ◽  
Structural Studies ◽  
Functional Theory ◽  
Nuclear Resonance Vibrational Spectroscopy ◽  
Ligand Interactions

<p>NO and O<sub>2</sub> are detoxified in many organisms using flavodiiron proteins (FDPs). The exact coordination of the iron centre in the active site of these enzymes remains unclear despite numerous structural studies. Here, we used <sup>57</sup>Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the iron-ligand interactions in <i>Escherichia coli</i> FDP. This data combined with density functional theory (DFT) and <sup>57</sup>Fe Mössbauer spectroscopy indicate that the oxidised form of FDP contains a dihydroxo-diferric Fe(III)–(µOH<sup>–</sup>)<sub>2</sub>–Fe(III) active site, while its reduction gives rise to a monohydroxo-diferrous Fe(II)–(µOH<sup>–</sup>)–Fe(II) site upon elimination of one bridging OH<sup>–</sup> ligand, thereby providing an open coordination site for NO binding. Prolonged NRVS data collection of the oxidised FDP resulted in photoreduction and formation of a partially reduced diiron center with two bridging hydroxyl ligands. These results have crucial implications for studying and understanding the mechanism of FDP as well as other non-haem diiron enzymes.</p>

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