14875-96-8Relevant academic research and scientific papers
Characterisation of Desulfovibrio vulgaris haem b synthase, a radical SAM family member
Lobo, Susana A.L.,Lawrence, Andrew D.,Rom?o, Célia V.,Warren, Martin J.,Teixeira, Miguel,Saraiva, Lígia M.
, p. 1238 - 1247 (2014)
An alternative route for haem b biosynthesis is operative in sulfate-reducing bacteria of the Desulfovibrio genus and in methanogenic Archaea. This pathway diverges from the canonical one at the level of uroporphyrinogen III and progresses via a distinct branch, where sirohaem acts as an intermediate precursor being converted into haem b by a set of novel enzymes, named the alternative haem biosynthetic proteins (Ahb). In this work, we report the biochemical characterisation of the Desulfovibrio vulgaris AhbD enzyme that catalyses the last step of the pathway. Mass spectrometry analysis showed that AhbD promotes the cleavage of S-adenosylmethionine (SAM) and converts iron-coproporphyrin III via two oxidative decarboxylations to yield haem b, methionine and the 5′-deoxyadenosyl radical. Electron paramagnetic resonance spectroscopy studies demonstrated that AhbD contains two [4Fe-4S]2 +/1 + centres and that binding of the substrates S-adenosylmethionine and iron-coproporphyrin III induces conformational modifications in both centres. Amino acid sequence comparisons indicated that D. vulgaris AhbD belongs to the radical SAM protein superfamily, with a GGE-like motif and two cysteine-rich sequences typical for ligation of SAM molecules and iron-sulfur clusters, respectively. A structural model of D. vulgaris AhbD with putative binding pockets for the iron-sulfur centres and the substrates SAM and iron-coproporphyrin III is discussed.
Heme bound amylin: Spectroscopic characterization, reactivity, and relevance to type 2 diabetes
Mukherjee, Soumya,Dey, Somdatta Ghosh
, p. 5226 - 5235 (2013)
Deposition of human amylin or islet amyloid polypeptide (hIAPP) within the β-cells of the pancreatic islet of Langerhans is implicated in the etiology of type 2 diabetes mellitus (T2Dm). Accumulating evidences suggest that increased body iron stores, iron overload, and, in particular, higher heme-iron intake is significantly associated with higher risk of Type 2 diabetes mellitus (T2Dm) (PloS One2012, 7, e41641). Some key pathological features of T2Dm, like iron dyshomeostasis, iron accumulation, mitochondrial dysfunction, and oxidative stress are very similar to the cytopathologies of Alzheimer's disease, which have been invoked to be due to heme complexation with amyloid β peptides. The similar etiology and pathogenic features in both Alzheimer's disease (AD) and T2Dm indicate a common underlying mechanism, with heme playing an important role. In this study we show that hIAPP can bind heme. His18 residue of hIAPP binds heme under physiological conditions and results in an axial high-spin active site with a trans-axial water derived ligand. Arg11 is a key residue that is also essential for heme binding. Heme(Fe2+)-hIAPP complexes are prone to produce partially reduced oxygen species (PROS). The His18 residue identified in this study is absent in rats which do not show T2Dm, implicating the significance of this residue as well as heme in the pathology of T2Dm.
The Moessbauer Spectrum of an Intermediate Spin (S = 1) Four-co-ordinated (Protoporphyrinato IX)Iron(II) Complex in a Frozen Aqueous Solution of Cetyltrimethylammonium Bromide
Medhi, Okhil K.,Silver, Jack
, p. 1199 - 1200 (1989)
The Moessbauer spectrum of the four-co-ordinated haem, (protoporphyrinato IX)iron(II) monodispersed in an aqueous detergent solution of 5percent cetyltrimethylammonium bromide (CTAB), is that of a typical intermediate spin (S = 1) system -1 and the quadrupole splitting (ΔEQ) is 1.44(2) mm s-1>; the results are comparable to those found in synthetic (porphyrinato)iron(II) analogues, the ΔEQ values follow the ? donating ability (basicity) of the porphyrin ligands and the two lines of the quadrupole doublet are of unequal intensity at 78 K.
The auxiliary [4Fe-4S] cluster of the Radical SAM heme synthase from: Methanosarcina barkeri is involved in electron transfer
Kühner, Melanie,Schweyen, Peter,Hoffmann, Martin,Ramos, José Vazquez,Reijerse, Edward J.,Lubitz, Wolfgang,Br?ring, Martin,Layer, Gunhild
, p. 4633 - 4643 (2016)
The heme synthase AhbD catalyzes the oxidative decarboxylation of two propionate side chains of iron-coproporphyrin III to the corresponding vinyl groups of heme during the alternative heme biosynthesis pathway occurring in sulfate-reducing bacteria and archaea. AhbD belongs to the family of Radical SAM enzymes and contains two [4Fe-4S] clusters. Whereas one of these clusters is required for substrate radical formation, the role of the second iron-sulfur cluster is not known. In this study, the function of the auxiliary cluster during AhbD catalysis was investigated. Two single cluster variants of AhbD from M. barkeri carrying either one of the two clusters were created. Using these enzyme variants it was shown that the auxiliary cluster is not required for substrate binding and formation of the substrate radical. Instead, the auxiliary cluster is involved in a late step of AhbD catalysis most likely in electron transfer from the reaction intermediate to a final electron acceptor. Moreover, by using alternative substrates such as coproporphyrin III, Cu-coproporphyrin III and Zn-coproporphyrin III for the AhbD activity assay it was observed that the central iron ion of the porphyrin substrate also participates in the electron transfer from the reaction intermediate to the auxiliary [4Fe-4S] cluster. Altogether, new insights concerning the completely uncharacterized late steps of AhbD catalysis were obtained.
CO rebinding to protoheme: Investigations of the proximal and distal contributions to the geminate rebinding barrier
Ye, Xiong,Yu, Anchi,Georgiev, Georgi Y.,Gruia, Florin,Ionascu, Dan,Cao, Wenxiang,Sage, J. Timothy,Champion, Paul M.
, p. 5854 - 5861 (2005)
The rebinding kinetics of CO to protoheme (FePPIX) in the presence and absence of a proximal imidazole ligand reveals the magnitude of the rebinding barrier associated with proximal histidine ligation. The ligation states of the heme under different solvent conditions are also investigated using both equilibrium and transient spectroscopy. In the absence of imidazole, a weak ligand (probably water) is bound on the proximal side of the FePPIX-CO adduct. When the heme is encapsulated in micelles of cetyltrimethylammonium bromide (CTAB), photolysis of FePPIX-CO induces a complicated set of proximal ligation changes. In contrast, the use of glycerol-water solutions leads to a simple two-state geminate kinetic response with rapid (10-100 ps) CO recombination and a geminate amplitude that can be controlled by adjusting the solvent viscosity. By comparing the rate of CO rebinding to protoheme in glycerol solution with and without a bound proximal imidazole ligand, we find the enthalpic contribution to the proximal rebinding barrier, Hp, to be 11 ± 2 kJ/mol. Further comparison of the CO rebinding rate of the imidazole bound protoheme with the analogous rate in myoglobin (Mb) leads to a determination of the difference in their distal free energy barriers: ΔGD ≈ 12 ± 1 kJ/mol. Estimates of the entropic contributions, due to the ligand accessible volumes in the distal pocket and the xenon-4 cavity of myoglobin (～3 kJ/mol), then lead to a distal pocket enthalpic barrier of HD ≈ 9 ± 2 kJ/mol. These results agree well with the predictions of a simple model and with previous independent room-temperature measurements (Tian et al. Phys. Rev. Lett. 1992, 68, 408) of the enthalpic MbCO rebinding barrier (18 ± 2 kJ/mol).
Spectroscopic characterization of hydroxide and aqua complexes of Fe(II)-protoheme, structural models for the axial coordination of the atypical heme of membrane cytochrome b6f complexes
Gomez De Gracia, Adrienne,Bordes, Luc,Desbois, Alain
, p. 17634 - 17643 (2005)
Electronic absorption and resonance Raman (RR) spectra are reported for hydroxide and aqua complexes of iron(II)-protoporphyrin IX (Fe(II)PP) respectively formed in alkaline and neutral aqueous solutions. These compounds with weak axial ligand(s) represent a biomimetic approach of the unusual coordination of the atypical heme ci of membrane cytochrome b 6f complexes. Absorption spectra and spectrophotometric titrations show that Fe(II)PP in alkaline aqueous cetyltrimethylammonium bromide (CTABr) binds one hydroxide ion, forming a five-coordinated high-spin (HS) complex. In alkaline aqueous ethanol, we confirm the formation of a dihydroxy complex of Fe(II)PP. In the RR spectra of Fe(II)PP dissolved in neutral aqueous CTABr, a mixture of a four-coordinated intermediate spin form with an HS monoaqua complex (Fe(II)PP(H2O)) was observed. The spectroscopic information obtained for Fe(II)PP(OH-), Fe(II)PP(H2O), and Fe(II)PP(OH -)2 was compared with that previously reported for the 2-methylimidazole and 2-methylimidazolate complexes of Fe(II)PP, representative of the most common axial ligation in HS heme proteins. This investigation reveals a very remarkable analogy in the spectral properties of, in one hand, the Fe(II)PP(H2O) and mono-2-methylimidazole complexes and, in the other hand, the Fe(II)PP(OH-) and mono-2-methylimidazolate complexes. The comparisons of the absorption and RR spectra of Fe(II)PP(OH-) and Fe(II)PP(OH-)2 clearly establish that both a redshift of the π-π electronic transitions and an upshift of the v8 RR frequency are spectral parameters indicative of porphyrin doming in HS ferrous complexes. Based upon isotopic substitutions (16OH, 16OD-, and 18OH-), stretching modes of the Fe-OH bond(s) of a ferrous porphyrin were assigned for the first time, i.e., at 435 cm-1 for Fe(II)PP(OH-) (ν(Fe(II)-OH -)) and at 421 cm-1 for Fe(II)PP(OH-) 2 (νs(Fe(II)-(OH-)2). The spectroscopic and redox properties of Fe(II)PP(H2O), Fe(II)PP(OH -), and heme ci were discussed and favor a water coordination for the heme ci iron.
Heme activates artemisinin more efficiently than hemin, inorganic iron, or hemoglobin
Zhang, Shiming,Gerhard, Glenn S.
, p. 7853 - 7861 (2008)
Artemisinin derivatives appear to mediate their anti-malarial through an initial redox-mediated reaction. Heme, inorganic iron, and hemoglobin have all been implicated as the key molecules that activate artemisinins. The reactions of artemisinin with diff
Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values
Silver, Jack,Al-Jaff, Golzar,Wilson, Michael T.,den Engelsen, Daniel,Fern, George R.,Ireland, Terry G.
, p. 297 - 313 (2022/03/08)
Studies are reported on the formation of low-spin six-coordinate [Fe(PPIX)L2] complexes from iron(II) protoporphyrin where L is one of a series of nitrogenous ligands (aliphatic, aromatic or heterocyclic). The bonding constants have been determined by titration of the metal complex with these ligands and are compared in relation to previous studies. The adduct formation was monitored utilising optical spectroscopy. In addition, M?ssbauer spectroscopic experiments were conducted to monitor the electronic environment around the central iron atom in these complexes. The two complementary spectroscopic methods indicated that all nitrogen ligands formed low-spin octahedral complexes. The magnitude of the overall binding constants (β2 values) are discussed and related to (a) the pKa values of the free ligands and (b) the M?ssbauer parameter ΔEQ, which represents the quadrupole splitting of the haem iron. The β2 and ΔEQ values are also discussed in terms of the structure of the ligand. Cooperative binding was observed for nearly all the ligands with Hill coefficients close to 2 for iron(II) protoporphyrin; one of these ligands displayed a much greater affinity than any we previously studied, and this was a direct consequence of the structure of the ligand. Overall conclusions on these and previous studies are drawn in terms of aliphatic ligands versus aromatic ring structures and the absence or presence of sterically hindered nitrogen atoms. The implications of the work for the greater understanding of haem proteins in general and in particular how the nitrogenous ligand binding results are relevant to and aid the understanding of the binding of inhibitor molecules to the cytochrome P450 mono-oxygenases (for therapeutic purposes) are also discussed. Graphical abstract: Changes in the electronic absorption spectra of five-coordinate [Fe(II)(PPIX)(2-MeIm)] that occurred as the temperature was lowered from room temperature to 78°?K [Figure not available: see fulltext.]
A METHOD FOR PREPARING SOY LEGHEMOGLOBIN USING ESCHERICHIA COLI
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Paragraph 00101-00102, (2021/07/17)
A method for preparing a soy leghemoglobin includes: constructing a first plasmid containing genes for heme biosynthesis pathway enzymes; constructing a second plasmid containing gene for Glycine max leghemoglobin LGB2; constructing a first Escherichia coli production host containing the first plasmid and the second plasmid; and producing the soy leghemoglobin by culturing the first Escherichia coli production host. A composition useful as a meat flavor and/or an iron supplement includes the soy leghemoglobin prepared in accordance with the method.
A METHOD FOR PREPARING PORCINE MYOGLOBIN USING ESCHERICHIA COLI
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Paragraph 00101-00102, (2021/07/17)
A method for preparing a porcine myoglobin includes: constructing a first plasmid containing genes for heme biosynthesis pathway enzymes; constructing a second plasmid containing a gene for Sus scrofa myoglobin MYG; constructing a first Escherichia coli production host containing the first plasmid and the second plasmid; and producing the porcine myoglobin by culturing the first Escherichia coli production host. A composition useful as a meat flavor and/or an iron supplement includes the porcine myoglobin prepared in accordance with the method.
