2 research outputs found
Nuclear Inelastic Scattering and Mòˆssbauer Spectroscopy as Local Probes for Ligand Binding Modes and Electronic Properties in Proteins: Vibrational Behavior of a Ferriheme Center inside a β-Barrel Protein
In this work, we present a study of the influence of
the protein matrix on its ability to tune the binding of small ligands
such as NO, cyanide (CN<sup>–</sup>), and histamine to the
ferric heme iron center in the NO-storage and -transport protein Nitrophorin
2 (NP2) from the salivary glands of the blood-sucking insect <i>Rhodnius prolixus</i>. Conventional Mòˆssbauer spectroscopy
shows a diamagnetic ground state of the NP2–NO complex and
Type I and II electronic ground states of the NP2–CN<sup>–</sup> and NP2–histamine complex, respectively. The change in the
vibrational signature of the protein upon ligand binding has been
monitored by Nuclear Inelastic Scattering (NIS), also called Nuclear
Resonant Vibrational Spectroscopy (NRVS). The NIS data thus obtained
have also been calculated by quantum mechanical (QM) density functional
theory (DFT) coupled with molecular mechanics (MM) methods. The calculations
presented here show that the heme ruffling in NP2 is a consequence
of the interaction with the protein matrix. Structure optimizations
of the heme and its ligands with DFT retain the characteristic saddling
and ruffling only if the protein matrix is taken into account. Furthermore,
simulations of the NIS data by QM/MM calculations suggest that the
pH dependence of the binding of NO, but not of CN<sup>–</sup> and histamine, might be a consequence of the protonation state of
the heme carboxyls
Nuclear Inelastic Scattering and Mòˆssbauer Spectroscopy as Local Probes for Ligand Binding Modes and Electronic Properties in Proteins: Vibrational Behavior of a Ferriheme Center inside a β-Barrel Protein
In this work, we present a study of the influence of
the protein matrix on its ability to tune the binding of small ligands
such as NO, cyanide (CN<sup>–</sup>), and histamine to the
ferric heme iron center in the NO-storage and -transport protein Nitrophorin
2 (NP2) from the salivary glands of the blood-sucking insect <i>Rhodnius prolixus</i>. Conventional Mòˆssbauer spectroscopy
shows a diamagnetic ground state of the NP2–NO complex and
Type I and II electronic ground states of the NP2–CN<sup>–</sup> and NP2–histamine complex, respectively. The change in the
vibrational signature of the protein upon ligand binding has been
monitored by Nuclear Inelastic Scattering (NIS), also called Nuclear
Resonant Vibrational Spectroscopy (NRVS). The NIS data thus obtained
have also been calculated by quantum mechanical (QM) density functional
theory (DFT) coupled with molecular mechanics (MM) methods. The calculations
presented here show that the heme ruffling in NP2 is a consequence
of the interaction with the protein matrix. Structure optimizations
of the heme and its ligands with DFT retain the characteristic saddling
and ruffling only if the protein matrix is taken into account. Furthermore,
simulations of the NIS data by QM/MM calculations suggest that the
pH dependence of the binding of NO, but not of CN<sup>–</sup> and histamine, might be a consequence of the protonation state of
the heme carboxyls