Moessbauer investigations of high-spin ferrous heme proteins. II. Chloroperoxidase, horseradish peroxidase, and hemoglobin

Champion, P. M.; Chiang, R.; Muenck, E.; Debrunner, Peter G.; Hager, Lowell P.

doi:10.1021/bi00690a002

Cited by 75 publications

(38 citation statements)

References 17 publications

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“…Stern and Peisach (46) first showed that a long wavelength Soret absorption band signifies the presence of a thiolate heme iron ligand in heme proteins. The presence of thiolate ligands in native CPO and P450 cytochromes has been confirmed by extensive spectroscopic techniques (22,(47)(48)(49)(50)) and x-ray crystallographic analysis (25,26). The Soret band for the ferrous-CO complexes of heme proteins containing an imidazole proximal ligand centers at 418-420 nm (51).…”

Section: Methodsmentioning

confidence: 90%

Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue

Mroczko

Manoj

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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Chloroperoxidase is a versatile heme enzyme which can cross over the catalytic boundaries of other oxidative hemoproteins and perform multiple functions. Chloroperoxidase, in addition to catalyzing classical peroxidative reactions, also acts as a P450 cytochrome and a potent catalase. The multiple functions of chloroperoxidase must be derived from its unique active site structure. Chloroperoxidase possesses a proximal cysteine thiolate heme iron ligand analogous to the P450 cytochromes; however, unlike the P450 enzymes, chloroperoxidase possesses a very polar environment distal to its heme prosthetic group and contains a glutamic acid residue in close proximity to the heme iron. The presence of a thiolate ligand in chloroperoxidase has long been thought to play an essential role in its chlorination and epoxidation activities; however, the research reported in this paper proves that hypothesis to be invalid. To explore the role of Cys-29, the amino acid residue supplying the thiolate ligand in chloroperoxidase, Cys-29 has been replaced with a histidine residue. Mutant clones of the chloroperoxidase genome have been expressed in a Caldariomyces fumago expression system by using gene replacement rather than gene insertion technology. C. fumago produces wild-type chloroperoxidase, thus requiring gene replacement of the wild type by the mutant gene. To the best of our knowledge, this is the first time that gene replacement has been reported for this type of fungus. The recombinant histidine mutants retain most of their chlorination, peroxidation, epoxidation, and catalase activities. These results downplay the importance of a thiolate ligand in chloroperoxidase and suggest that the distal environment of the heme active site plays the major role in maintaining the diverse activities of this enzyme.

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Section: Methodsmentioning

confidence: 90%

Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue

Mroczko

Manoj

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

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“…The study of Champion et al 37 found the isomer shift to be 0.90 mm/s and the quadrupole splitting constant 2.70 mm/s but that the sign is opposite to that of the globins (i.e. positive).…”

Section: Hydrogen Bonding Effectsmentioning

confidence: 97%

“…The value is very similar to that observed reduced HRP (2.70 mm/s, 4.2 K) with its known hydrogen-bonded histidine. 37 …”

Section: Hydrogen Bonding Effectsmentioning

confidence: 99%

All high-spin (S = 2) iron(ii) hemes are NOT alike

Schulz

Scheidt

2015

Dalton Trans.

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A common structural motif in heme proteins is a five-coordinate species in which the iron is coordinated by a histidyl residue. The widely distributed heme proteins with this motif are essential for the well being of humans and other organisms. We detail the differences in molecular structures and physical properties of high-spin iron(II) porphyrin derivatives ligated by neutral imidazole, hydrogen bonded imidazole, and imidazolate or other anions. Two distinct (high spin) electronic states are observed that have differing d-orbital occupancies and discernibly different five-coordinate square-pyramidal coordination groups. The doubly occupied orbital in the imidazole species is a low symmetry orbital oblique to the heme plane whereas in the imidazolate species the doubly occupied orbital is a high symmetry orbital in the heme plane, i.e., the primary doubly-occupied d-orbital is different. Methods that can be used to classify a particular complex into one or the other state includes X-ray structure determinations, high-field Mössbauer spectroscopy, vibrational spectroscopy, magnetic circular dichroism, and even-spin EPR spectroscopy. The possible functional significance of the ground state differences has not been established for heme proteins, but is likely found in the pathways for oxygen transport vs. oxygen utilization.

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“…These results are strikingly similar to those observed for protein examples. Reduced HRP was studied by Mössbauer spectroscopy and compared with deoxymyoglobin 17, 18. These Mössbauer studies, in a strong magnetic field, showed remarkable differences between reduced HRP and deoxymyoglobin even though both are five-coordinate hemes with histidine as the axial ligand.…”

Section: Introductionmentioning

confidence: 99%

Just a Proton: Distinguishing the Two Electronic States of Five-Coordinate High-Spin Iron(II) Porphyrinates with Imidazole/ate Coordination

Sulok

Paulat

et al. 2010

J. Am. Chem. Soc.

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We report detailed studies on two S = 2 electronic states of high-spin iron(II) porphyrinates. These two states are exemplified by the five-coordinate derivatives with either neutral imidazole or anionic imidazolate as the axial ligand. The application of several physical methods all demonstrate distinctive differences between the two states. These include characteristic molecular structure differences, Mössbauer spectra, magnetic circular dichroism spectroscopy, and integer-spin EPR spectral distinctions. These distinctions are supported by DFT calculations. The two states are characterized by very different spatial properties of the doubly occupied orbital of the high-spin species that are consonant with the physical properties.

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Moessbauer investigations of high-spin ferrous heme proteins. II. Chloroperoxidase, horseradish peroxidase, and hemoglobin

Cited by 75 publications

References 17 publications

Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue

Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue

All high-spin (S = 2) iron(ii) hemes are NOT alike

Just a Proton: Distinguishing the Two Electronic States of Five-Coordinate High-Spin Iron(II) Porphyrinates with Imidazole/ate Coordination

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