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Full-Text Articles in Physics
Spectroscopic And Thermodynamic Characterization Of The E151d And E151a Altered Leucine Aminopeptidases From Aeromonas Proteolytica, Krzysztof P. Bzymek, Sabina I. Swierczek, Brian Bennett, Richard C. Holz
Spectroscopic And Thermodynamic Characterization Of The E151d And E151a Altered Leucine Aminopeptidases From Aeromonas Proteolytica, Krzysztof P. Bzymek, Sabina I. Swierczek, Brian Bennett, Richard C. Holz
Physics Faculty Research and Publications
Previous kinetic characterization of the glutamate 151 (E151)-substituted forms of the leucine aminopeptidase from Aeromonas proteolytica (Vibrio proteolyticus; AAP) has provided critical evidence that this residue functions as the general acid/base. The close proximity of similar glutamate residues to the bridging water/hydroxide of the dinuclear active sites of metalloenzymes (2.80 and 3.94 Å in carboxypeptidase G2 and 3.30 and 3.63 Å in AAP), suggests it may also be involved in stabilizing the active-site metal ions. Therefore, the structural perturbations of the dinuclear active site of AAP were examined for two E151-substituted forms, namely E151D-AAP and E151A-AAP, by …
Spectroscopic Studies On Cobalt(Ii)-Substituted Metallo-Β-Lactamase Imis From Aeromonas Veronii Bv. Sobria, Patrick A. Crawford, Ke-Wu Yang, Narayan Sharma, Brian Bennett, Michael W. Crowder
Spectroscopic Studies On Cobalt(Ii)-Substituted Metallo-Β-Lactamase Imis From Aeromonas Veronii Bv. Sobria, Patrick A. Crawford, Ke-Wu Yang, Narayan Sharma, Brian Bennett, Michael W. Crowder
Physics Faculty Research and Publications
In an effort to probe the structure of a group Bb metallo-β-lactamase, Co(II)-substituted ImiS was prepared and characterized by electronic absorption, NMR, and EPR spectroscopies. ImiS containing 1 equiv of Co(II) (Co(II)1-ImiS) was shown to be catalytically active. Electronic absorption studies of Co(II)1-ImiS revealed the presence of two distinct features: (1) an intense sulfur to Co(II) ligand to metal charge transfer band and (2) less intense, Co(II) ligand field transitions that suggest 4-coordinate Co(II) in Co(II)1-ImiS. 1H NMR studies of Co(II)1-ImiS suggest that one histidine, one aspartic acid, and one cysteine …
Both Nucleophile And Substrate Bind To The Catalytic Fe(Ii)-Center In The Type-Ii Methionyl Aminopeptidase From Pyrococcus Furiosus, Alicja J. Copik, Sarah Waterson, Sabina I. Swierczek, Brian Bennett, Richard C. Holz
Both Nucleophile And Substrate Bind To The Catalytic Fe(Ii)-Center In The Type-Ii Methionyl Aminopeptidase From Pyrococcus Furiosus, Alicja J. Copik, Sarah Waterson, Sabina I. Swierczek, Brian Bennett, Richard C. Holz
Physics Faculty Research and Publications
Metalloproteases utilize their active site divalent metal ions to generate a nucleophilic water/hydroxide. For methionine aminopeptidases (MetAPs), the exact location of this nucleophile, as well as of the substrate, with respect to the active site metal ion is unknown. In order to address this issue, we have examined the catalytically competent Fe(II)-loaded form of PfMetAP-II ([Fe(PfMetAP-II)]) in the absence and presence of both nitric oxide (NO) and the substrate-analogue inhibitor butaneboronic acid (BuBA) by kinetic and spectroscopic (EPR, UV−vis) methods. NO binds to [Fe(PfMetAP−II)] with a Kd of 200 μM forming an {FeNO}7 …
Direct Evidence That The Reaction Intermediate Of Metallo-Β-Lactamase L1 Is Metal Bound, James D. Garrity, Brian Bennett, Michael W. Crowder
Direct Evidence That The Reaction Intermediate Of Metallo-Β-Lactamase L1 Is Metal Bound, James D. Garrity, Brian Bennett, Michael W. Crowder
Physics Faculty Research and Publications
In an effort to probe the structure of the reaction intermediate of metallo-β-lactamase L1 when reacted with nitrocefin and other β-lactams, time-dependent absorption and rapid-freeze-quench (RFQ) EPR spectra were obtained using the Co(II)-substituted form of the enzyme. When using nitrocefin as the substrate, time-dependent absorption spectra demonstrate that Co(II)-substituted L1 utilizes a reaction mechanism, similar to that of the native Zn(II) enzyme, in which a short-lived intermediate forms. RFQ-EPR spectra of this intermediate demonstrate that the binding of substrate results in a change in the electronic properties of one or both of the Co(II)'s in the enzyme …