A5010506045- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Hemoglobin structure and function
- Porphyrin and Phthalocyanine Chemistry
- Nitric Oxide and Endothelin Effects
- Metal-Catalyzed Oxygenation Mechanisms
- Magnetism in coordination complexes
- Crystallography and molecular interactions
- Metal complexes synthesis and properties
- Electrochemical sensors and biosensors
- Neonatal Health and Biochemistry
- Heme Oxygenase-1 and Carbon Monoxide
- Electrochemical Analysis and Applications
- Hemoglobinopathies and Related Disorders
- Molecular Sensors and Ion Detection
- Porphyrin Metabolism and Disorders
- Electron Spin Resonance Studies
- Clostridium difficile and Clostridium perfringens research
- Inorganic and Organometallic Chemistry
- Structural and Chemical Analysis of Organic and Inorganic Compounds
- Mass Spectrometry Techniques and Applications
- Organometallic Complex Synthesis and Catalysis
- Erythrocyte Function and Pathophysiology
- Crystal structures of chemical compounds
- Chemical Reactions and Mechanisms
University of Oklahoma
2016-2025
Rice Institute
2022
Norman Regional Hospital
2015-2021
Southern Illinois University Edwardsville
2006-2016
University of Michigan
2013
University of California, Santa Barbara
2009
Virginia Commonwealth University
2008
University at Buffalo, State University of New York
2000-2006
Buffalo State University
2006
University of Exeter
2004-2005
It is now well-established that mammalian heme proteins are reactive with various nitrogen oxide species and these reactions may play significant roles in physiology. For example, the ferrous protein myoglobin (Mb) has been shown to reduce nitrite (NO2−) nitric (NO) under hypoxic conditions. We demonstrate here distal pocket histidine residue (His64) of horse heart metMbIII (i.e., ferric MbIII) marked effects on mode ion coordination iron center. X-ray crystal structures were determined for...
The nitrite anion is known to oxidize and degrade hemoglobin (Hb). Recent literature reports suggest a reductase activity for Hb, converting into nitric oxide. Surprisingly, no structural information about Hb−nitrite interactions has been reported. We have determined the crystal structure of ferric complex at 1.80 Å resolution. ligand adopts uncommon O-nitrito binding mode. In addition, nitrito conformations in α β subunits are different, reflecting subtle effects distal His orienting
Nitric oxide (NO) and its derivatives such as nitrite hyponitrite are biologically important species of relevance to human health. Much their physiological stems from interactions with the iron centers in heme proteins. The chemical reactivities displayed by heme−NOx (NOx = NO, nitrite, hyponitrite) a function binding modes NOx ligands. Hence, an understanding types extant compounds is if we unravel inherent properties these metabolites. In this Forum Article, experimentally characterized...
Heme-HNO species are crucial intermediates in several biological processes. To date, no well-defined Fe heme-HNO model compounds have been reported. Hydride attack on the cationic ferric [(OEP)Fe(NO)(5-MeIm)]OTf (OEP = octaethylporphyrinato dianion) generates an Fe-HNO product that has characterized by IR and (1)H NMR spectroscopy. Results of DFT calculations reveal a direct hydride N atom coordinated nitrosyl.
The six-coordinate nitrosyl σ-bonded aryl(iron) and -(ruthenium) porphyrin complexes (OEP)Fe(NO)(p-C6H4F) (OEP)Ru(NO)(p-C6H4F) (OEP = octaethylporphyrinato dianion) have been synthesized characterized. Single-crystal X-ray structure determinations reveal an unprecedented bending tilting of the MNO group for both {MNO}6 species as well significant lengthening trans axial bond distances. In Fe−N−O angle is 157.4(2)°, nitrogen atom tilted off normal to heme plane by 9.2°, Fe−N(NO) 1.728(2) Å,...
A critical component of the biological activity NO and nitrite involves their coordination to iron center in heme proteins. Irradiation (330 < λ 500 nm) nitrosyl−nitro compound (TPP)Fe(NO)(NO2) (TPP = tetraphenylporphyrinato dianion) at 11 K results changes IR spectrum associated with both nitro-to-nitrito nitrosyl-to-isonitrosyl linkage isomerism. Only isomer is obtained 200 K, indicating that isonitrosyl less stable than nitrito isomer. DFT calculations reveal two ground-state...
The coupling of two nitric oxide (NO) molecules in heme active sites is an important contributor to the conversion NO nitrous (N2O) by heme-containing enzymes. Several formulations for presumed heme-Fe{N2O2}n- intermediates have been proposed previously, however, no crystal structures systems reported date. We report first isolation and characterization a stable bimetallic hyponitrite iron porphyrin, [(OEP)Fe]2(μ-N2O2), prepared from reaction [(OEP)Fe]2(μ-O) with hyponitrous acid. Density...
Exposure of a single crystal the nitrite adduct ferric myoglobin (Mb) at 100 K to high-intensity synchrotron X-ray radiation resulted in changes UV−vis spectrum that can be attributed reduction compound ferrous derivative. We employed correlated single-crystal spectroscopy with crystallography further characterize this photoproduct. The 1.55 Å resolution structure photoproduct reveals retention O-binding mode for binding iron center. data are consistent cryogenic generation and trapping, K,...
The detoxification of nitric oxide (NO) by bacterial NO reductase (NorBC) represents a paradigm how can be detoxified anaerobically in cells. In order to elucidate the mechanism this enzyme, model complexes provide convenient means assess potential reaction intermediates. particular, there have been many proposed mechanisms that invoke formation hyponitrite bridge between heme b3 and nonheme iron (FeB) centers within NorBC active site. However, reactivity bridged has not investigated much...
Several cobalt nitrosyl porphyrins of the form (T(p/m-X)PP)Co(NO) (p/m-X = p-OCH(3) (1), p-CH(3) (2), m-CH(3) (3), p-H (4), m-OCH(3) (5), p-OCF(3) (6), p-CF(3) (7), p-CN (8)) have been synthesized in 30-85% yields by reaction precursor porphyrin with nitric oxide. Compounds 1-7 were also prepared nitrosonium tetrafluoroborate followed reduction cobaltocene. 1-8 characterized elemental analysis, IR and (1)H NMR spectroscopy, mass spectrometry, UV-vis spectrophotometry. They are diamagnetic...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFirst Observation of Photoinduced Nitrosyl Linkage Isomers Iron PorphyrinsLin Cheng, Irina Novozhilova, Chris Kim, Andrey Kovalevsky, Kimberly A. Bagley, Philip Coppens, and George B. Richter-AddoView Author Information Department Chemistry State University New York at Buffalo Buffalo, 14260-3000 College York, 14222 Biochemistry Oklahoma, 620 Parrington Oval Norman, 73019 Cite this: J. Am. Chem. Soc. 2000, 122, 29, 7142–7143Publication Date...
The NO ligand in the formally {FeNO}6 compound [Fe(oep)(NO)(thiolate)] is bent, and does not impart a significant structural trans effect to Fe–S bond.
This study presents Nuclear Resonance Vibrational Spectroscopy (NRVS) data on the five-coordinate (5C) ferrous heme−nitrosyl complex [Fe(OEP)(NO)] (1, OEP2− = octaethylporphyrinato dianion) and corresponding 15N18O labeled complex. The obtained spectra identify two isotope sensitive features at 522 388 cm−1, which shift to 508 381 respectively, upon labeling. These are assigned Fe−NO stretch ν(Fe−NO) in-plane Fe−N−O bending mode δip(Fe−N−O), latter has been unambiguously for first time 1....
Two ruthenium nitrosyl porphyrins have been synthesized and characterized by spectroscopic electrochemical methods. The investigated compounds are represented as [(TPP)Ru(NO)(H(2)O)]BF(4) (TPP)Ru(NO)(ONO) where TPP is the dianion of 5,10,15,20-tetraphenylporphyrin. crystallizes in tetragonal space group I4, with a = 13.660(1) Å, c 9.747(1) V 1818.7(3) Å(3), Z 2, 233 K. most chemically interesting feature structure that O-bound nitrito groups located axial trans to one another. Both complexes...
Nitrosamines are well-known for their toxic and carcinogenic properties. The metabolic activation of nitrosamines occurs via interaction with the heme-containing cytochrome P450 enzymes. We report preparation structural characterization a number nitrosamine adducts synthetic iron porphyrins. reactions cations [(por)Fe(THF)2]ClO4 (por = TPP, TTP, OEP) dialkylnitrosamines (R2NNO; R2 Me2, Et2, (cyclo-CH2)4, (cyclo-CH2)5, (PhCH2)2) in toluene generate six-coordinate high-spin (S 5/2)...
Bacterial NO reductase (bacNOR) enzymes utilize a heme/non-heme active site to couple two molecules N2O. We show that BF3 coordination the nitrosyl O-atom in (OEP)Fe(NO) activates it toward N–N bond formation with generate 15N-isotopic labeling reveals reversible exchange reaction and follow-up N–O cleavage N2O step. Other Lewis acids (B(C6F5)3 K+) also promote coupling (OEP)Fe(NO). These results, complemented by DFT calculations, provide experimental support for cis:b3 pathway bacNOR.
Hydride attack at a ferric heme-NO to give an Fe-HNO intermediate is key step in the global N-cycle. We demonstrate differential reactivity when six- and five-coordinate models react with hydride. Although formation thermodynamically favored from this reaction, Fe-H kinetically for 5C case.