Models of the cytochromes b. 5. EPR studies of low-spin iron(III) tetraphenylporphyrins

Walker, F. Ann; Reis, David A.; Balke, Virginia L.

doi:10.1021/ja00335a003

Cited by 148 publications

(147 citation statements)

References 5 publications

Supporting

Mentioning

137

Contrasting

Order By: Relevance

“…Additional evidence for the formation of a low spin ferric heme is obtained from EPR spectra of the dialyzed homogenates with or without 1 mM histamine added to the sample. A loss of the signal at g = 6 is observed, but no new signals appeared in the g = 2.8-3.0, 2.3, and 1.5-1.7 regions, as expected for a hexacoordinated, low spin ferric heme protein (16) (Fig. 4).…”

Section: Spectral Properties Of the Histamine-nitrophorin Complexsupporting

confidence: 77%

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

Ribeiro

Walker

1994

The Journal of Experimental Medicine

140

View full text Add to dashboard Cite

Summal'yThe salivary glands of Rhodnius prolixus contain a nitrosyl-heme protein, named nitrophorin, that releases the vasodilatory and antiplatelet compound nitric oxide (NO). Because imidazole compounds such as histamine can interact with Fe(III) heme proteins, we investigated whether such substances could interact with Rhodnius nitrophorins. Both imidazole and histamine, but not histidine can produce full change of the difference spectra of the Soret band in the 1-3 #M concentration range (at a heme protein concentration of 0.4 #M). The apparent Ko.5 for the binding of histamine with the heme protein is below 1 #M. Furthermore, the complex histamine-heme protein does not dissociate after molecular sieving chromatography. To investigate whether histamine could displace NO from the native nitrosyl nitrophorins, histamine was added to the native heme proteins, leading to displacement of the bound NO as observed by changes in the absorption spectra as well as by the production of nitrite. Finally, the antihistamine effect of the heme protein was demonstrated by its inhibition of the histamine-provoked contractures of the guinea pig ileum. It is concluded that histamine, a common autacoid found at the site of injury and exposure to antigenic substances such as the site of feeding by hematophagous arthropods, can be scavenged by the nitrosyl nitrophorin of R. prolixus, which, in return, will release the vasodilatory and platelet inhibiting NO to counteract the host hemostatic response.

show abstract

Section: Spectral Properties Of the Histamine-nitrophorin Complexsupporting

confidence: 77%

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

Ribeiro

Walker

1994

The Journal of Experimental Medicine

140

View full text Add to dashboard Cite

show abstract

“…Therefore, one or both of the histidine ligands of heme a 605 in SoxABCD most likely form a stronger hydrogen bond with a neighboring amino acid side chain than the corresponding hydrogen bond in isolated SoxB. In fact, in model compounds of low spin hemes, strong hydrogen bonds have shown an effect similar to the deprotonation of the histidine ligands (59,60). Furthermore, the strong hydrogen bond can also explain the red shift of the Soret band of SoxABCD relative to SoxB; the increased basicity of the histidine ligands may allow the optical transition of the heme to occur at lower energy.…”

Section: Discussionmentioning

confidence: 99%

The Archaeal SoxABCD Complex Is a Proton Pump in Sulfolobus acidocaldarius

Gleißner

Kaiser

Antonopoulos

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

The thermoacidophilic archaeon Sulfolobus acidocaldarius expresses a very unusual quinol oxidase, which contains four heme a redox centers and one copper atom. The enzyme was solubilized with dodecyl maltoside and purified to homogeneity by a combination of hydrophobic interaction and anion exchange chromatography. The oxidase complex consists of four polypeptide subunits with apparent molecular masses of 64, 39, 27, and 14 kDa that are encoded by the soxABCD operon (Lü bben, M., Kolmerer, B., and Saraste, M. (1992) EMBO J. 11, 805-812). The optical spectra and redox potentials of the SoxABCD complex have been characterized, and the absorption coefficients of the contributing cytochromes a 587 and aa 3 were determined. The EPR spectra indicate the presence of three low spin and one high spin heme species, the latter associated with the binuclear heme Cu B site. Standard midpoint potentials of the cytochrome a 587 heme centers were determined as ؉210 and ؉270 mV, respectively. The maximum turnover of the complex (1300 s ؊1 at 65°C) was found to be about three times greater than that of the previously studied isolated cytochrome aa 3 subunit alone (Gleissner, ؉ /e ؊ ratio >1 was determined, identifying the SoxABCD complex as a proton-pumping quinol oxidase. According to structural analysis, the cytochrome aa 3 moiety of the complex does not contain the signature of a H ؉ pumping channel as identified in Rhodobacter sphaeroides or Paracoccus denitrificans. Therefore, for H ؉ translocation, a mechanism different from that in typical heme-copper oxidases of the aa 3 or bo 3 type is discussed.M

show abstract

“…This EPR spectral type has been called large g max 13 or highly anisotropic low-spin (HALS). 14 The origin of the large g max EPR spectrum was first studied in the complex [Fe(TPP)(2-MeHIm) 2 26 with parallel axial ligands and a high-spin state.…”

Section: Introductionmentioning

confidence: 99%

Low-Spin Bis(2-methylimidazole)(octaethylporphyrinato)iron(III) Chloride (perp-[Fe(OEP)(2-MeHIm)₂]Cl): A Consequence of Hydrogen Bonding?

Noll

Schulz

et al. 2006

Inorg. Chem.

View full text Add to dashboard Cite

show abstract

Models of the cytochromes b. 5. EPR studies of low-spin iron(III) tetraphenylporphyrins

Cited by 148 publications

References 5 publications

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

The Archaeal SoxABCD Complex Is a Proton Pump in Sulfolobus acidocaldarius

Low-Spin Bis(2-methylimidazole)(octaethylporphyrinato)iron(III) Chloride (perp-[Fe(OEP)(2-MeHIm)₂]Cl): A Consequence of Hydrogen Bonding?

Contact Info

Product

Resources

About

Models of the cytochromes b. 5. EPR studies of low-spin iron(III) tetraphenylporphyrins

Cited by 148 publications

References 5 publications

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

High affinity histamine-binding and antihistaminic activity of the salivary nitric oxide-carrying heme protein (nitrophorin) of Rhodnius prolixus.

The Archaeal SoxABCD Complex Is a Proton Pump in Sulfolobus acidocaldarius

Low-Spin Bis(2-methylimidazole)(octaethylporphyrinato)iron(III) Chloride (perp-[Fe(OEP)(2-MeHIm)2]Cl): A Consequence of Hydrogen Bonding?

Contact Info

Product

Resources

About

Low-Spin Bis(2-methylimidazole)(octaethylporphyrinato)iron(III) Chloride (perp-[Fe(OEP)(2-MeHIm)₂]Cl): A Consequence of Hydrogen Bonding?