Figure - uploaded by Hanna Lewandowska
Content may be subject to copyright.
![Scheme 6 Some of the important iron-sulfur cluster units found in metalloenzymes. [2Fe-2S] rhombus cluster is characteristic of [2Fe-2S] ferredoxins and Rieskie proteins, [4Fe-4S] cubanee.g., in [4Fe-4S] ferredoxins, aconitase; [3Fe-4S] clusters are present in the inactive form of aconitase, [3Fe-4S] ferredoxins. The iron vertices, designated as [Fe], have high-spin tetrahedral FeS 4 coordination. Reprinted from [140], with the permission of Elsevier, copyright 2000](profile/Hanna-Lewandowska/publication/281729792/figure/fig1/AS:638817274966021@1529317315832/Scheme-6-Some-of-the-important-iron-sulfur-cluster-units-found-in-metalloenzymes.png)
Scheme 6 Some of the important iron-sulfur cluster units found in metalloenzymes. [2Fe-2S] rhombus cluster is characteristic of [2Fe-2S] ferredoxins and Rieskie proteins, [4Fe-4S] cubanee.g., in [4Fe-4S] ferredoxins, aconitase; [3Fe-4S] clusters are present in the inactive form of aconitase, [3Fe-4S] ferredoxins. The iron vertices, designated as [Fe], have high-spin tetrahedral FeS 4 coordination. Reprinted from [140], with the permission of Elsevier, copyright 2000
Source publication
A comprehensive overview is presented of the biologically relevant coordination chemistry of nitrosyls and its biochemical consequences. Representative classes of metal nitrosyls are introduced along with the structural and bonding aspects that may have consequences for the biological functioning of these complexes. Next, the biological targets and...
Similar publications
The relation between electronic structure and cohesion of materials has been a permanent quest of Jacques Friedel and his school. He developed simple models that are of great value as guidelines in conjunction with ab initio calculations. His local approach of bonding has both the advantages of a large field of applications including non-crystallin...
![Electronic density isosurfaces [ρ(r) = 0.001 e Å⁻³] of the LUMO state...](publication/312365265/figure/fig4/AS:11431281189058846@1694887727358/Electronic-density-isosurfaces-rr-0001-e-A-of-the-LUMO-state-electron-density_Q320.jpg)
Applying density functional theory (DFT) calculations, we predict the structural and electronic properties of different types of palladium–fullerene polymers. We examine the structures of one- (1-D), two- (2-D), and three-dimensional (3-D) polymers. We find that the most stable polymer is that represented by bonding via the [6,6] position of the fu...
![Figure 5. Natural orbital occupations for the 4 B3g state of [V6N6] +...](publication/332431045/figure/fig4/AS:748145977864194@1555383309595/Natural-orbital-occupations-for-the-4-B3g-state-of-V6N6-with-a-CAS11-11-active_Q320.jpg)
Density Functional Theory and Complete Active Space Self-Consistent Field (CASSCF) methodologies are used to explore the electronic structure of the cationic V–N clusters, [V4N4]+ and [V6N6]+, that have been identified in recent mass spectrometric experiments. Our calculations indicate that both clusters are based on cubane-like fragments of the ro...
In this work, the structural stability and the electronic properties of LiNiBO 3 and LiFe x Ni (1-x) BO 3 are studied using first principle calculations based on density functional theory. The calculated structural parameters are in good agreement with the available theoretical data. The most stable phases of the Fe substituted systems are predicte...
![Reaction of with [Li2(Me3SiC3SiMe3)]](publication/332580226/figure/fig5/AS:11431281183603919@1692956234802/Reaction-of-with-Li2Me3SiC3SiMe3_Q320.jpg)
The synthesis of an unusual 1-metalla-2,3-cyclobutadiene complex [rac-(ebthi)Ti(Me3SiC3SiMe3)] (rac-ebthi = rac-1,2-ethylene-1,1’-bis(η⁵-tetrahydroindenyl)), a metallacyclic analogue of a non-existent four-membered 1,2-cyclobutadiene is described. By variation of the cyclopentadienyl ligand of the titanocene precursor it was possible to stabilise t...
Citations
... However, the specific proteins that are targeted during DNIC formation can vary depending on the cell type and physiological context [5]. Biosynthesis of DNICs was first discovered in 1964 [19], and continued investigations revealed tetrahedral [(NO)2Fe(L)2] complex, as a natural and ubiquitous DNIC formed from interaction of • NO with non-heme iron-sulphur ([Fe-S]) proteins and cellular labile iron pool [8,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. ...
Pretreatment of cells with proteolysis inhibitors diminished intensity and changed shape of DNICs specific EPR signal in a treatment time-dependent manner. The level of DNIC formation was significantly influenced by the presence of protein degradation products. Interestingly, formation of HMWDNICs depended on the availability of LMWDNICs. The extent of glutathione involvement in the in vivo formation of DNICs is minor yet noticeable, aligning with our prior research findings.
... NO· is isoelectronic with the dioxygen monocation (O 2 + ), and NO + is isoelectronic with CO and CN -, while NOis isoelectronic with O 2 , having a triplet ground state. Bonding between a NOligand and a metal accounts for the formation of metal-nitrosyl (M-NO) complexes, which have structural and electronic analogies with biological oxygen activators (Lewandowska, 2013). ...
Nitric oxide (NO) once regarded as a poisonous air pollutant, is now appreciated as a regulatory molecule essential for several biological functions in plants. In this review we not only summarize NO generation in different plant organs and cellular compartments, we also discuss the role of NO in Fe homeostasis particularly in Fe-deficient plants. Fe is one of the most limiting essential nutrient element for plants. Plants often exhibit Fe deficiency symptoms despite of sufficient tissue Fe concentration. NO appears to be not only upregulating Fe uptake mechanisms but it also makes it more bioavailable for metabolic functions. NO forms complexes with Fe which can then be delivered into target cells/ tissues. NO generated in plants can alleviate oxidative stress by regulating antioxidant defence processes probably by improving functional Fe status and by inducing post-translational modifications in the enzymes/proteins involved in the antioxidant defence responses. It is hypothesized that NO acts in cooperation with transcription factors such as bHLH, FIT and IRO (Iron-transcription factor) to regulate expression of enzymes and proteins essential for Fe homeostasis. However, further investigations are needed to unentangle the interaction of NO with the intracellular target molecules which lead to an enhanced internal Fe availability in plants.
... Thus, it appeared interesting to find out, if the lipoprotein is able to undergo the process of iron-nitrosylation, commonly observed for other proteins and what is the biological fate of the DNIC-modified LDL particles. DNICs with proteins are well known as biological transducers of NO [20,21]. Indeed, DNIC-modification of a protein introduces two important biological agents: NO and Fe. ...
... The most recognized moieties of iron-nitrosyl group coordination in proteins are sulfhydryl groups of cysteines [32]. These soft Lewis bases have an excellent affinity to the Fe(NO) group [21]. Indeed, ApoB100 with its 24 cysteines is the richest in thiols among lipoprotein constituents (see Supporting Information Fig. 6 for cysteine location in ApoB100). ...
In view of the interrelations between NO, Fe, and LDL in the cardiovascular system it appears interesting to find out, if the lipoprotein particles undergo the process of iron-nitrosylation, commonly observed for other proteins and what is the biological fate of iron-nitrosylated LDL particles. Iron-nitrosylated LDL preparation containing Fe(NO)2 motif (DNICLDL) was obtained and characterized for the first time. In order to test its interactions with potential target cells, DNICLDL was administered to the hepatoma HepG2 cells. The effects were referred to those induced by native LDL (nLDL) and oxidized LDL (oxLDL) particles. DNICLDL administration considerably increased total iron content in the studied cell line, but did not influence the level of calcein-chelatable ions. DNICLDL was found to be low toxic to cells. The study suggests that DNICLDL might be a potential transducer of iron.
... DNICs possess two NO groups and two thiolate ligands; the former can be thiol groups of proteins (protein-bound, or high molecular weight DNICs) or free thiols (low molecular weight DNICs). DNICs, together with S-nitrosothiols, are thought to be storage and transport forms of NO [8][9][10]. At the same time, DNICs are NO donors that decompose through non-enzymatic mechanism. ...
We studied effects of NO-donor iron nitrosyl complex with N-ethylthiourea ligand (ETM) on normal or tumor-derived cell lines. ETM was mildly toxic to most cell lines studied except the human glioma cell line A172 that proved to be highly sensitive to the complex and underwent cell death after ETM exposure. The high susceptibility of A172 cells to ETM was attributed to its NO-donor properties since no toxicity was detected for the N-ethylthiourea ligand.
... It is known that in the octahedral complex Mn(CN) 5 (NO) 3 the IR bands characterizing coordinated nitrosyl group occur at nearly 1700 cm -1 [12,20]. In given case, the Me-N-O bond is nearly linear [21] (deviation no more than 9°). However, if we assume that nitrosyl group in the octahedral complex occupies one coordination site and o-phenanthroline molecule is too large to occur in the bridging position, than it is rather probable that one of the o-phenanthroline molecules is completly removed with subsequent transfer to the external coordination sphere to release the second coordination site, which can be occupied by the molecule of other ligand (e.g. ...
The conditions of pertechnetate ion precipitation with ferroin nitrate in nitric acid solutions were determined. The effect of precipitation condition on the composition and structure of ferroin pertechnetate complexes was analyzed. At aging of the precipitate in the mother liquor the formation of nitrosyl group in the complex was found, which is confirmed by appearance in the IR spectrum of the band at 1700 cm−1 belonging to the coordinated nitrosyl group. Analysis of the IR spectra of ferroin perrhenate and pertechnetate complexes showed that coordinated nitrosyl group is formed only in the presence of technetium in the complex structure.
Glutathione transferases are detoxification enzymes with multifaceted roles, including a role in the metabolism and scavenging of nitric oxide (NO) compounds in cells. Here, we explored the ability of Trametes versicolor glutathione transferases (GSTs) from the Omega class (TvGSTOs) to bind metal-nitrosyl compounds. TvGSTOs have been studied previously for their ligandin role and are interesting models to study protein‒ligand interactions. First, we determined the X-ray structure of the TvGSTO3S isoform bound to the dinitrosyl glutathionyl iron complex (DNGIC), a physiological compound involved in the storage of nitric oxide. Our results suggested a different binding mode compared to the one previously described in human GST Pi 1 (GSTP1). Then, we investigated the manner in which TvGSTO3S binds three nonphysiological metal-nitrosyl compounds with different metal cores (iron, ruthenium and osmium). We assayed sodium nitroprusside, a well-studied vasodilator used in cases of hypertensive crises or heart failure. Our results showed that the tested GST can bind metal-nitrosyls at two distinct binding sites. Thermal shift analysis with six isoforms of TvGSTOs identified TvGSTO6S as the best interactant. Using the Griess method, TvGSTO6S was found to improve the release of nitric oxide from sodium nitroprusside in vitro, whereas the effects of human GST alpha 1 (GSTA1) and GSTP1 were moderate. Our results open new structural perspectives for understanding the interactions of glutathione transferases with metal-nitrosyl compounds associated with the biochemical mechanisms of NO uptake/release in biological systems.
Nitric oxide (NO) is an important signaling molecule that is involved in a wide range of physiological and pathological events in biology. Metal coordination chemistry, especially with iron, is at the heart of many biological transformations involving NO. A series of heme proteins, nitric oxide synthases (NOS), soluble guanylate cyclase (sGC), and nitrophorins, are responsible for the biosynthesis, sensing, and transport of NO. Alternatively, NO can be generated from nitrite by heme- and copper-containing nitrite reductases (NIRs). The NO-bearing small molecules such as nitrosothiols and dinitrosyl iron complexes (DNICs) can serve as an alternative vehicle for NO storage and transport. Once NO is formed, the rich reaction chemistry of NO leads to a wide variety of biological activities including reduction of NO by heme or non-heme iron-containing NO reductases and protein post-translational modifications by DNICs. Much of our understanding of the reactivity of metal sites in biology with NO and the mechanisms of these transformations has come from the elucidation of the geometric and electronic structures and chemical reactivity of synthetic model systems, in synergy with biochemical and biophysical studies on the relevant proteins themselves. This review focuses on recent advancements from studies on proteins and model complexes that not only have improved our understanding of the biological roles of NO but also have provided foundations for biomedical research and for bio-inspired catalyst design in energy science.
This contribution deals with the structure and reactivity of bound nitrosyl in transition-metal centers (group 8: Fe, Ru, Os). The focus is set on pseudooctahedral nitrosyl-complexes with coordination number 5 and 6, containing ancillary coligands of both heme- and nonheme type. The discussion is organized in terms of Enemark and Feltham's classification, selecting complexes within the {MNO}n framework (n=6, 7, and 8). The examples have been chosen for a best description of the electronic structures in terms of modern structural, spectroscopical, and computational methodologies. The selected {MNO}6,7,8 species reflect the occurrence of three redox states of bound nitrosyl, frequently (though not always) described as NO+, NO, and NO- for n=6, 7, and 8, respectively. The analysis is centered on the members of a series of complexes for which the three redox states have been observed on the same platform, viz., [Fe(CN)5(NO)]2,3,4- and [Ru(Me3[9]aneN3)(bpy)(NO)]3,2,1+, in aqueous solutions. The influence of the donor-acceptor character of the coligands is specifically addressed with emphasis on the ligand trans- to nitrosyl, showing that the latter group may exert a delabilizing influence (as NO+), as well as a labilizing one (NO-≫NO) on the trans-ligand. On the other hand, typical electrophilic reactivity patterns (toward different nucleophiles) are analyzed for M-NO+, and nucleophilic reactivity (with O2) is described for the reduced species, M-NO and M-(NO-). In the latter case, protonation is described by characterizing the bound HNO species. Important differences are highlighted in the chemistry of bound NO- and HNO, revealing the strong and mild reductant abilities of these species, respectively. The chemistry is analyzed in terms of the biological relevance to the behavior of nitrite- and NO-reductases and other NO-related enzymes.
Dinitrosyl iron (I) complexes (DNICs), intracellular NO donors, are important factors in nitric oxide-dependent regulation of cellular metabolism and signal transduction. It has been shown that NO diminishes toxicity of iron ions and vice versa. To gain insight into a possible role of DNIC in this phenomenon, we examined the effect of DNIC(GS)2 formation on the ability of iron ions to mediate DNA damage, by treatment of pUC19 plasmid with physiologically relevant concentrations of DNIC(GS)2. It was shown, that DNIC(GS)2 formation protects against the genotoxic effect of iron ions alone and iron ions in the presence of naturally abundant antioxidant, GSH. This sheds a new light on the iron-related protective effect of NO in the circumstances of the oxidative stress.
