Read by QxMD icon Read

Heme iron

Jing-Hua Chen, Long-Jiang Yu, Alain Boussac, Zheng-Yu Wang-Otomo, Tingyun Kuang, Jian-Ren Shen
The thermophilic purple sulfur bacterium Thermochromatium tepidum possesses four main water-soluble redox proteins involved in the electron transfer behavior. Crystal structures have been reported for three of them: a high potential iron-sulfur protein, cytochrome c', and one of two low-potential cytochrome c 552 (which is a flavocytochrome c) have been determined. In this study, we purified another low-potential cytochrome c 552 (LPC), determined its N-terminal amino acid sequence and the whole gene sequence, characterized it with absorption and electron paramagnetic spectroscopy, and solved its high-resolution crystal structure...
April 24, 2018: Photosynthesis Research
Claire Kruger, Yuting Zhou
On October 26, 2015, IARC published a summary of their findings regarding the association of cancer with consumption of red meat or processed meat (IARC 2015a; The Lancet Oncology 2015). The Working Group concluded that there is limited evidence in human beings for carcinogenicity from the consumption of red meat and inadequate evidence in experimental animals for the carcinogenicity of consumption of red meat. Nevertheless, the working group concluded that there is strong mechanistic evidence by which ingestion of red meat can be linked to human colorectal cancer and assigned red meat to Group 2A "probably carcinogenic to humans"...
April 21, 2018: Food and Chemical Toxicology
Shane M Huebner, Kaylee K Helfrich, Nipun Saini, Sharon E Blohowiak, Adrienne A Cheng, Pamela J Kling, Susan M Smith
BACKGROUND: Prenatal alcohol exposure (PAE) causes neurodevelopmental disability. Clinical and animal studies show gestational iron deficiency exacerbates PAE's behavioral and growth deficits. In rat, PAE manifests an inability to establish iron homeostasis, increasing hepcidin (maternal and fetal) and fetal liver iron while decreasing brain iron and promoting anemia. Here, we hypothesize dietary iron fortification during pregnancy may mitigate alcohol's disruption of fetal iron homeostasis...
April 19, 2018: Alcoholism, Clinical and Experimental Research
Chen Cai, Andy O Leu, Guo-Jun Xie, Jianhua Guo, Yuexing Feng, Jian-Xin Zhao, Gene W Tyson, Zhiguo Yuan, Shihu Hu
Microbially mediated anaerobic oxidation of methane (AOM) is a key process in the regulation of methane emissions to the atmosphere. Iron can serve as an electron acceptor for AOM, and it has been suggested that Fe(III)-dependent AOM potentially comprises a major global methane sink. Although it has been proposed that anaerobic methanotrophic (ANME) archaea can facilitate this process, their active metabolic pathways have not been confirmed. Here we report the enrichment and characterisation of a novel archaeon in a laboratory-scale bioreactor fed with Fe(III) oxide (ferrihydrite) and methane...
April 16, 2018: ISME Journal
Christopher Perry, Emmanuel L C de Los Santos, Lona M Alkhalaf, Gregory L Challis
Covering: up to the end of 2017The roles played by Rieske non-heme iron-dependent oxygenases in natural product biosynthesis are reviewed, with particular focus on experimentally characterised examples. Enzymes belonging to this class are known to catalyse a range of transformations, including oxidative carbocyclisation, N-oxygenation, C-hydroxylation and C-C desaturation. Examples of such enzymes that have yet to be experimentally investigated are also briefly described and their likely functions are discussed...
April 13, 2018: Natural Product Reports
Francisco Cabezas, Carolina Mascayano
Lipoxygenases (LOX) are enzymes that catalyze polyunsaturated fatty acid peroxidation and have a non-heme iron atom located in their active site. They are implicated in the arachidonic acid pathway and involved in inflammation, fever, pain production and in the origins of several diseases such as cancer, asthma and psoriasis. The search for inhibitors of these enzymes has emerged in the last years, and isoflavonoids have a broad spectrum of biological activity with low cytotoxicity. Our previous results have shown that isoflavonoids inhibited different LOX isoforms in vitro...
April 6, 2018: Journal of Biomolecular Structure & Dynamics
Rudra N Samajdar, Dhivya Manogaran, S Yashonath, Aninda J Bhattacharyya
Quasi reversibility in electrochemical cycling between different oxidation states of iron is an often seen characteristic of iron containing heme proteins that bind dioxygen. Surprisingly, the system becomes fully reversible in the bare iron-porphyrin complex: hemin. This leads to the speculation that the polypeptide bulk (globin) around the iron-porphyrin active site in these heme proteins is probably responsible for the electrochemical quasi reversibility. To understand the effect of such polypeptide bulk on iron-porphyrin, we study the interaction of specific amino acids with the hemin center in solution...
April 5, 2018: Physical Chemistry Chemical Physics: PCCP
Kyle D Sutherlin, Brent S Rivard, Lars H Böttger, Lei V Liu, Melanie S Rogers, Martin Srnec, Kiyoung Park, Yoshitaka Yoda, Shinji Kitao, Yasuhiro Kobayashi, Makina Saito, Makoto Seto, Michael Hu, Jiyong Zhao, John D Lipscomb, Edward I Solomon
The Rieske dioxygenases are a major subclass of mononuclear non-heme iron enzymes that play an important role in bioremediation. Recently, a high-spin FeIII -(hydro)peroxy intermediate (BZDOp) has been trapped in the peroxide shunt reaction of benzoate 1,2-dioxygenase. Defining the structure of this intermediate is essential to understanding the reactivity of these enzymes. Nuclear resonance vibrational spectroscopy (NRVS) is a recently developed synchrotron technique that is ideal for obtaining vibrational, and thus structural, information on Fe sites, as it gives complete information on all vibrational normal modes containing Fe displacement...
April 4, 2018: Journal of the American Chemical Society
Eduard J van Beers, Richard van Wijk
Sickle cell disease (SCD) is a monogenetic disorder marked by hemolytic anemia and vaso-occlusive complications. The hallmark of SCD is the intracellular polymerization of sickle hemoglobin (HbS) after deoxygenation, and the subsequent characteristic shape change (sickling) of red cells. Vaso-occlusion occurs after endothelial activation, expression of adhesion molecules and subsequent adhesion of leucocytes and sickle erythrocytes to the vascular wall. Here we review how oxidative stress from various sources influences this process...
2018: Clinical Hemorheology and Microcirculation
Benjamin E R Snyder, Lars H Böttger, Max L Bols, James J Yan, Hannah M Rhoda, Ariel B Jacobs, Michael Y Hu, Jiyong Zhao, E Ercan Alp, Britt Hedman, Keith O Hodgson, Robert A Schoonheydt, Bert F Sels, Edward I Solomon
Iron-containing zeolites exhibit unprecedented reactivity in the low-temperature hydroxylation of methane to form methanol. Reactivity occurs at a mononuclear ferrous active site, α-Fe(II), that is activated by N2 O to form the reactive intermediate α-O. This has been defined as an Fe(IV)=O species. Using nuclear resonance vibrational spectroscopy coupled to X-ray absorption spectroscopy, we probe the bonding interaction between the iron center, its zeolite lattice-derived ligands, and the reactive oxygen...
April 2, 2018: Proceedings of the National Academy of Sciences of the United States of America
Elena Maklashina, Sany Rajagukguk, T M Iverson, Gary Cecchini
Complex II (SdhABCD) is a membrane-bound component of mitochondrial and bacterial electron transport chains as well as of the TCA cycle. In this capacity, it catalyzes the reversible oxidation of succinate. SdhABCD contains the SDHA protein harboring a covalently bound FAD redox center and the iron-sulfur (Fe-S) protein SDHB, containing three distinct Fe-S centers. When assembly of this complex is compromised, the flavoprotein SDHA may accumulate in the mitochondrial matrix or bacterial cytoplasm. Whether the unassembled SDHA has any catalytic activity, for example, in succinate oxidation, fumarate reduction, reactive oxygen species (ROS) generation, or other off-pathway reactions is not known...
April 2, 2018: Journal of Biological Chemistry
Ryan C McCarthy, Jose Carlo Sosa, Andrew M Gardeck, Andrew S Baez, Chih-Hao Lee, Marianne Wessling-Resnick
Microglia are immune cells of the central nervous system and are implicated in brain inflammation. However, how brain microglia modulate transport and metabolism of the essential metal iron in response to pro- and anti-inflammatory environmental cues is unclear. Here, we characterized uptake of transferrin (Tf)-bound iron (TBI) and non-Tf-bound iron (NTBI) by immortalized microglial (IMG) cells. We found that these cells preferentially take up NTBI in response to the proinflammatory stimulus lipopolysaccharide (LPS) or amyloid-beta (Aβ)...
April 2, 2018: Journal of Biological Chemistry
René Ullrich, Marzena Poraj-Kobielska, Steffi Scholze, Claire Halbout, Martin Sandvoss, Marek J Pecyna, Katrin Scheibner, Martin Hofrichter
Two unspecific peroxygenases (UPO, EC from the basidiomycetous fungi Marasmius rotula and Marasmius wettsteinii oxidized steroids with hydroxyacetyl and hydroxyl functionalities at C17 - such as cortisone, Reichstein's substance S and prednisone - via stepwise oxygenation and final fission of the side chain. The sequential oxidation started with the hydroxylation of the terminal carbon (C21) leading to a stable geminal alcohol (e.g. cortisone 21-gem-diol) and proceeded via a second oxygenation resulting in the corresponding α-ketocarboxylic acid (e...
March 26, 2018: Journal of Inorganic Biochemistry
Jill M Cholette, Anthony P Pietropaoli, Kelly F Henrichs, George M Alfieris, Karen S Powers, Francisco Gensini, Jeffrey S Rubenstein, Dawn Sweeney, Richard Phipps, Sherry L Spinelli, Majed A Refaai, Michael P Eaton, Neil Blumberg
BACKGROUND: There are data suggesting that free hemoglobin (Hb), heme, and iron contribute to infection, thrombosis, multiorgan failure, and death in critically ill patients. These outcomes may be mitigated by haptoglobin. STUDY DESIGN AND METHODS: 164 consecutively treated children undergoing surgery for congenital heart disease were evaluated for associations between free Hb and haptoglobin and clinical outcomes, physiologic metrics, and biomarkers of inflammation RESULTS: Higher perioperative free Hb levels (and lower haptoglobin levels) were associated with mortality, nosocomial infection, thrombosis, hours of intubation and inotropes, increased interleukin-6, peak serum lactate levels, and lower nadir mean arterial pressures...
March 30, 2018: Transfusion
Hsia-Lien Lin, Haoming Zhang, Paul F Hollenberg
17α-Ethynylestradiol (EE), a major component of many oral contraceptives, affects the activities of a number of the human cytochrome P450 (CYP) enzymes. Here, we characterized the effect of EE on CYP2J2, a major human CYP isoform which participates in metabolism of arachidonic acid. EE inactivated the hydroxyebastine carboxylation activity of CYP2J2 in a reconstituted system. The loss of activity is time- and concentration-dependent and requires NADPH. K I and k inact values for the inactivation were 3.6 μM and 0...
March 30, 2018: Drug Metabolism and Disposition: the Biological Fate of Chemicals
Juan Chen, Duenpen Unjaroen, Stepan Stepanovic, Annie van Dam, Maja Gruden, Wesley R Browne
Non-heme iron(II) complexes of pentadentate N4Py ( N,N-bis(2-pyridylmethyl)- N-bis(2-pyridyl)methylamine) type ligands undergo visible light-driven oxidation to their iron(III) state in the presence of O2 without ligand degradation. Under mildly basic conditions, however, highly selective base catalyzed ligand degradation with O2 , to form a well-defined pyridyl-imine iron(II) complex and an iron(III) picolinate complex, is accelerated photochemically. Specifically, a pyridyl-CH2 moiety is lost from the ligand, yielding a potentially N4 coordinating ligand containing an imine motif...
March 30, 2018: Inorganic Chemistry
Ying-Ying Li, Lian-Peng Tong, Rong-Zhen Liao
The mononuclear [Cl-FeIII (dpa)-Cl]+ (1Cl ) complex containing a square planar tetradentate polypyridine ligand has been reported to catalyze water oxidation in pH = 1 aqueous medium with ceric ammonium nitrate (CAN) as a chemical oxidant. The reaction mechanism of the oxygen evolution driven by this catalyst was investigated by means of density functional calculations. The results showed that one chloride ligand of 1Cl has to exchange with a water molecule to generate 1, [Cl-FeIII (dpa)-OH2 ]2+ , as the starting species of the catalytic cycle...
March 30, 2018: Inorganic Chemistry
Manish B Shah, Qinghai Zhang, James R Halpert
The over two dozen CYP2B structures of human, rabbit, and woodrat enzymes solved in the last decade have significantly enhanced our understanding of the structure-function relationships of drug metabolizing enzymes. More recently, an important role has emerged for halogen-π interactions in the CYP2B6 active site in substrate selectivity, explaining in part the preference for halogenated ligands as substrates. The mechanism by which such ligands interact with CYP2B enzymes involves conserved phenylalanine side chains, in particular F108, F115, or F297, in the active site, which form π bonds with halogens...
March 29, 2018: International Journal of Molecular Sciences
Giovanni Li Manni, Ali Alavi
Spin fluctuations in Fe(II)-porphyrins are at the heart of heme-proteins functionality. Despite significant progress in porphyrin chemistry, the mechanisms that rule spin state stabilization remain elusive. Here, it is demonstrated by using multiconfigurational quantum chemical approaches, including the novel Stochastic-CASSCF method, that electron delocalization between the metal centre and the π system of the macrocycle differentially stabilizes the triplet spin states over the quintet. This delocalization takes place via charge-transfer excitations, involving the π system of the macrocycle and the out-of-plane iron d orbitals, key linking orbitals between metal and macrocycle...
March 29, 2018: Journal of Physical Chemistry. A
Nathchar Naowarojna, Ronghai Cheng, Li Chen, Melissa Quill, Meiling Xu, Changming Zhao, Pinghua Liu
As one of the most abundant elements on earth, sulfur is part of many small molecular metabolites and often plays key roles in their biological activities. Over the last few decades, some general strategies were discovered for the incorporation of "S" into natural products. In this review, we summarized recent efforts on elucidating the biosynthetic details for two sulfur-containing metabolites, ergothioneine and ovothiol. Their biosyntheses involves an unprecedented trans-sulfur strategy: a combination of a mononuclear non-heme iron enzyme catalyzed oxidative C-S bond formation reaction and a PLP-enzyme catalyzed C-S lyase reaction...
March 28, 2018: Biochemistry
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"