Separation and identification of the regioisomers of verdoheme by reversed-phase ion-pair high-performance liquid chromatography, and characterization of their complexes with heme oxygenase

Sakamoto, Hiroshi; Omata, Yoshiaki; Adachi, Yoshio; Palmer, Graham; Noguchi, Masato

doi:10.1016/s0162-0134(00)00149-5

Cited by 35 publications

(53 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hemin was obtained from Sigma. Ferrous α-verdoheme (hereafter referred to as verdoheme) was synthesized and purified as reported previously [11]. Formation of ferrous verdoheme was confirmed by its optical absorption spectrum (λ max in aqueous pyridine solution: 397, 505, 534 and 679 nm).…”

Section: Experimental Materialsmentioning

confidence: 99%

“…Formation of ferrous verdoheme was confirmed by its optical absorption spectrum (λ max in aqueous pyridine solution: 397, 505, 534 and 679 nm). Concentration of the bispyridine complex of verdoheme was determined spectrophotometrically using ε 397 = 53.3 mM −1 cm −1 [11]. All spectrophotometric analyses were conducted on a Varian Cary 50 Bio UV-visible spectrophotometer at 25 °C.…”

Section: Experimental Materialsmentioning

confidence: 99%

“…The reconstitution and purification of verdoheme-rHO-1 complex were performed as reported previously [11]. Unless otherwise stated, the following manipulations were carried out anaerobically in a UNILAB glove box system (MBRAUN, Garching, Germany) filled with N 2 gas.…”

Section: Preparation Of Heme-and Ferrous Verdoheme-rho-1 Complexesmentioning

confidence: 99%

“…The first step is the oxidation of heme to α-hydroxyheme, requiring O 2 and two electrons [6][7][8]. The second step, also requiring O 2 and an electron, is the formation of ferrous α-verdoheme from α-hydroxyheme with the concomitant release of hydroxylated α-meso carbon as CO [9][10][11][12]. The third step is the conversion of ferrous α-verdoheme to a ferric biliverdin-iron chelate for which, once again, O 2 and three electrons are required [13].…”

Section: Introductionmentioning

confidence: 99%

“…The degradation of verdoheme is the least understood of the three successive oxygenation reactions during HO catalysis [13,15]. It has been well known that hydrolysis of verdoheme to biliverdin can take place in acidic solution [11]. However, the enzymatic degradation of verdoheme to ferric biliverdin-iron chelate by HO requires O 2 and reducing equivalents [16][17][18] and both lactam oxygen atoms present in the biliverdin-iron chelate derive from molecular oxygen [19,20].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1

Satō

Higashimoto

Sakamoto

et al. 2007

Journal of Inorganic Biochemistry

Self Cite

View full text Add to dashboard Cite

The heme oxygenase (HO) reaction consists of three successive oxygenation reactions, i.e. heme to α-hydroxyheme, α-hydroxyheme to verdoheme, and verdoheme to biliverdin-iron chelate. Of these, the least understood step is the conversion of verdoheme to biliverdin-iron chelate. For the cleavage of the oxaporphyrin ring of ferrous verdoheme, involvement of a verdoheme π-neutral radical has been proposed. To probe this hypothetical mechanism in the HO reaction, we performed electrochemical reduction of ferrous verdoheme complexed with rat HO-1 under anaerobic conditions. On the basis of the electrochemical spectral changes, the midpoint potential for the oneelectron reduction of the oxaporphyrin ring of ferrous verdoheme was found to be −0.47 ± 0.01 V vs the normal hydrogen electrode (NHE). Because this potential is far lower than those of both flavins of NADPH-cytochrome P450 reductase, and of NADPH, it is concluded that the one-electron reduction of the oxaporphyrin ring of ferrous verdoheme is unlikely to occur and that the formation of the π-neutral radical cannot be the initial step in the degradation of verdoheme by HO. Rather, it appears more reasonable to consider an alternative mechanism in which binding of O 2 to the ferrous iron of verdoheme is the first step in the degradation of verdoheme.

show abstract

Section: Experimental Materialsmentioning

confidence: 99%

Section: Experimental Materialsmentioning

confidence: 99%

Section: Preparation Of Heme-and Ferrous Verdoheme-rho-1 Complexesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1

Satō

Higashimoto

Sakamoto

et al. 2007

Journal of Inorganic Biochemistry

Self Cite

View full text Add to dashboard Cite

show abstract

Tyrosine oxidation in heme oxygenase: examination of long-range proton-coupled electron transfer

Смирнов

Roth

2014

J Biol Inorg Chem

View full text Add to dashboard Cite

Heme oxygenase is responsible for the degradation of a histidine-ligated ferric protoporphyrin IX (Por) to biliverdin, CO, and the free ferrous ion. Described here are studies of tyrosyl radical formation reactions that occur after oxidizing Fe(III)(Por) to Fe(IV)=O(Por(·+)) in human heme oxygenase isoform-1 (hHO-1) and the structurally homologous protein from Corynebacterium diphtheriae (cdHO). Site-directed mutagenesis on hHO-1 probes the reduction of Fe(IV)=O(Por(·+)) by tyrosine residues within 11 Å of the prosthetic group. In hHO-1, Y58· is implicated as the most likely site of oxidation, based on the pH and pD dependent kinetics. The absence of solvent deuterium isotope effects in basic solutions of hHO-1 and cdHO contrasts with the behavior of these proteins in the acidic solution, suggesting that long-range proton-coupled electron transfer predominates over electron transfer.

show abstract

Conversion of a heme-based oxygen sensor to a heme oxygenase by hydrogen sulfide: effects of mutations in the heme distal side of a heme-based oxygen sensor phosphodiesterase (Ec DOS)

Liu

Yan

et al. 2013

Biometals

View full text Add to dashboard Cite

The heme-based oxygen-sensor phosphodiesterase from Escherichia coli (Ec DOS), is composed of an N-terminal heme-bound oxygen sensing domain and a C-terminal catalytic domain. Oxygen (O2) binding to the heme Fe(II) complex in Ec DOS substantially enhances catalysis. Addition of hydrogen sulfide (H2S) to the heme Fe(III) complex in Ec DOS also remarkably stimulates catalysis in part due to the heme Fe(III)-SH and heme Fe(II)-O2 complexes formed by H2S. In this study, we examined the roles of the heme distal amino acids, M95 (the axial ligand of the heme Fe(II) complex) and R97 (the O2 binding site in the heme Fe(II)-O2 complex) of the isolated heme-binding domain of Ec DOS (Ec DOS-PAS) in the binding of H2S under aerobic conditions. Interestingly, R97A and R97I mutant proteins formed an oxygen-incorporated modified heme, verdoheme, following addition of H2S combined with H2O2 generated by the reactions. Time-dependent mass spectroscopic data corroborated the findings. In contrast, H2S did not interact with the heme Fe(III) complex of M95H and R97E mutants. Thus, M95 and/or R97 on the heme distal side in Ec DOS-PAS significantly contribute to the interaction of H2S with the Fe(III) heme complex and also to the modification of the heme Fe(III) complex with reactive oxygen species. Importantly, mutations of the O2 binding site of the heme protein converted its function from oxygen sensor to that of a heme oxygenase. This study establishes the novel role of H2S in modifying the heme iron complex to form verdoheme with the aid of reactive oxygen species.

show abstract

Separation and identification of the regioisomers of verdoheme by reversed-phase ion-pair high-performance liquid chromatography, and characterization of their complexes with heme oxygenase

Cited by 35 publications

References 37 publications

Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1

Electrochemical reduction of ferrous α-verdoheme in complex with heme oxygenase-1

Tyrosine oxidation in heme oxygenase: examination of long-range proton-coupled electron transfer

Conversion of a heme-based oxygen sensor to a heme oxygenase by hydrogen sulfide: effects of mutations in the heme distal side of a heme-based oxygen sensor phosphodiesterase (Ec DOS)

Contact Info

Product

Resources

About