Mössbauer spectroscopy as a probe of electric field in heme pocket of deoxyheme proteins: theoretical approach

Abstract

Chemical reactions taking place in active centers of different enzymes are controlled by electric fields created by the protein in these centers. These electric fields can be experimentally detected by different experimental techniques (infrared absorption, NMR, etc.). In this paper, we use quantum chemical calculations to show that Mössbauer spectroscopy can be also used to study protein electric field. We study effect of both the model and protein electric fields on the magnitude of quadrupole splitting of Mössbauer spectra of the high-spin ferrous myoglobin and its models. It is shown that the quadrupole splitting is notably affected by the protein electric field. This result also explains a number of the experimental data.

Accurate Prediction of Mössbauer Hyperfine Parameters in Bis-Axially Coordinated Iron(II) Phthalocyanines Using Density Functional Theory Calculations: A Story of a Single Orbital Revealed by Natural Bond Orbital Analysis

“…Although low-spin iron(II) phthalocyanines with axially coordinated phosphorus donors have been known since the mid-1970s, 75,76 this is the first crystal structure reported for this class of coordination compounds. The phthalocyanine ligand in the centrosymmetric structure of PcFe(PMe 3 ) 2 is planar, and the PMe 3 ligands are nearly perpendicular to the phthalocyanine plane [P1−Fe1−N1 = 90.89 (6) o and P1−Fe1−N3 = 91.09 (6) o ]. The Fe−N(Pc) bond distances are within the typical range of bis-axially coordinated iron(II) phthalocyanines (Supporting Information Table S4).…”

“…Because of their versatile role in a wide variety of biochemical oxygen- and electron-transfer processes, heme and iron-cluster proteins can be considered key to the existence of life on our planet. Thanks to its ability to provide metal-specific information amidst enormously intricate biochemical settings, 57 Fe Mössbauer spectroscopy has played a significant role in unravelling the mystery of heme protein function. − In order to identify the key intermediates in complex catalytic pathways, however, scientists often need to deconvolute complicated Mössbauer spectra based on chemical intuition and support provided by theoretical models. Thus, the ability to accurately predict 57 Fe Mössbauer hyperfine parameters becomes critical in many cases.…”

Binding of Carbon Monoxide to Hemoglobin in an Oxygen Environment: Force Field Development for Molecular Dynamics

“…To unveil the rupture of the Fe heme –CO coordination bond in an O 2 -rich environment via MD simulations, we reparameterize the coordination interactions between heme and GLs with a classical FF that is compatible with CHARMM, ,, by DFT calculations to give ground-truth Fe heme –GL energy and by Car–Parrinello molecular dynamics (CPMD) simulations to obtain the equilibrium Fe heme –O–O angle at room temperature. − We parametrize the Fe heme –CO interactions by fitting the coordination potential energy landscape with a Lennard–Jones (LJ) function. We parametrize the Fe heme –O 2 interactions using a feedforward neural network (FNN) model that is trained according to a series of MD simulation results for revealing the correlation between FF parameters and bond energy plus equilibrium angle.…”

Accurate Prediction of the Excited States in the Fully Conjugated Porphyrin Tapes across the Full Spectral Range: A Story of the Interplay between π–π* and Intramolecular Charge-Transfer Transitions in Soft Chromophores

“…Porphyrins are well-known compounds that have attracted research interest for many years due to their relevance in biology, − catalysis, − and medicine. − The application of porphyrins and similar functional dyes in the textile industry, chemo- and electrochromic devices, − photodynamic cancer therapy, − optical recording, , and light harvesting − relies on their photophysical properties. Thus, accurate prediction of the energies and intensities of excited states in such systems is crucial for the in silico design of new synthetic porphyrins with predefined optical properties.…”