Resonance Raman spectra of highly oxidized metalloporphyrins and heme proteins

Kitagawa, Teizo; Mizutani, Yasuhisa

doi:10.1016/0010-8545(94)80081-2

Cited by 113 publications

(121 citation statements)

References 157 publications

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“…The frequencies observed for the mesoheme-HRP-II derivative, relative to the resting state species, are entirely consistent with expectations and the behavior observed for other ferryl heme-containing enzymes (20). Thus, 2 , 3 , 4 , 10 , and 11 shift to higher frequencies by 9 -20 cm Ϫ1 , compared to their positions for the ferric derivative.…”

Section: Mesoheme-reconstituted Hrpsupporting

confidence: 75%

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Resonance Raman Spectra of Native and Mesoheme-reconstituted Horseradish Peroxidase and Their Catalytic Intermediates

Kincaid

Zheng

Al-Mustafa

et al. 1996

Journal of Biological Chemistry

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Resonance Raman studies of native and mesohemereconstituted horseradish peroxidase and their catalytic intermediates, known as Compounds I and II, have been conducted using both near UV (ϳ350 nm) and visible (406.7 nm) excitation. Careful power studies indicate that the authentic Compound I spectra are obtainable using near UV excitation, but that use of visible excitation results in contamination of the Compound I spectrum with the spectrum of a Compound II-like photoproduct. Using H 2 18 O 2 , the (Fe‫؍‬O) stretching modes for both systems are unambiguously identified, for the first time, at ϳ790 cm ؊1 . The authentic Compound I spectra are indicative of an 2 A 1u -like ground state for both the native and the mesoheme-reconstituted proteins. Finally, the possible biological implications of such information are briefly discussed.

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Section: Mesoheme-reconstituted Hrpsupporting

confidence: 75%

“…4). Assignment of the higher frequency marker modes are made with reference to well-documented previous assignments for metalloporphyrins (40 -42) and other heme proteins (20,38,39). These assignments, along with the observed shifts upon methyl group deuteration, are summarized in Table I.…”

Section: Mesoheme-reconstituted Hrpmentioning

confidence: 99%

Resonance Raman Spectra of Native and Mesoheme-reconstituted Horseradish Peroxidase and Their Catalytic Intermediates

Kincaid

Zheng

Al-Mustafa

et al. 1996

Journal of Biological Chemistry

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“…Consistent with this interpretation, FeAO in F shows a more substantial H 2 O͞D 2 O frequency shift (24,54) and the oxo oxygen is more readily exchanged with solvent water (23). The hydrogen-bonding change at the FeAO moiety in F relative to P (1998) will affect both the optical properties of the heme chromophore and the vibrational properties of the HisOFe IV AO structure (50,(55)(56)(57)(58) (Table 1). Variation in the basicity of the proximal histidine is also a likely contributor to the optical and vibrational differences between the two intermediates.…”

supporting

confidence: 62%

Dioxygen activation and bond cleavage by mixed-valence cytochrome c oxidase

Proshlyakov

Pressler

Babcock

1998

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

323

374

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Elucidating the structures of intermediates in the reduction of O 2 to water by cytochrome c oxidase is crucial to understanding both oxygen activation and proton pumping by the enzyme. In the work here, the reaction of O 2 with the mixed-valence enzyme, in which only heme a 3 and Cu B in the binuclear center are reduced, has been followed by time-resolved resonance Raman spectroscopy. The results show that OAO bond cleavage occurs within the first 200 s after reaction initiation; the presence of a uniquely stable FeOOOO(H) peroxy species is not detected. The product of this rapid reaction is a heme a 3 oxoferryl (Fe IV AO) species, which requires that an electron donor in addition to heme a 3 and Cu B must be involved. The available evidence suggests that the additional donor is an amino acid side chain. Recent crystallographic data [Yoshikawa, S., Shinzawa-Itoh, K., Nakashima, R., Yaono, R., Yamashita, E. OOH؊ , and the tyrosyl radical. This mechanism provides molecular structures for two key intermediates that drive the proton pump in oxidase; moreover, it has clear analogies to the proposed OOO bond forming chemistry that occurs during O 2 evolution in photosynthesis.The molecular mechanism of dioxygen activation and reduction by the terminal respiratory enzyme, cytochrome c oxidase (CcO), is accessible because of its unique kinetic properties. Elucidation of this mechanism is of fundamental importance in understanding O 2 chemistry in biological systems and necessary for insight into the function of the protein as a redox-linked proton pump. CcO uses four redox-active metal centers, Cu A , heme a, and the heme a 3 ͞Cu B binuclear center, to sustain mitochondrial electron transport by reducing molecular oxygen to water. This reaction ensures a constant flow of electrons through the respiratory chain and the coupled generation of a proton gradient across the mitochondrial membrane, which is required for ATP synthesis. The oxygen chemistry catalyzed by CcO contributes directly to the build-up of the proton gradient because of its redox-linked proton pumping function (1). Thus, the overall reaction catalyzed by CcO may be written aswhere H in ϩ and H out ϩ indicate protons on the matrix (in) and cytosolic (out) sides of the membrane. Because its reaction kinetics is controlled by its proton-pumping function, unique insights into oxygen activation mechanisms are possible (2, 3).A number of reaction intermediates in dioxygen reduction have been identified recently (3, 4). Nonetheless, the timing and mechanism of the critical OAO bond cleavage process in the heme a 3 ͞Cu B binuclear center and the structure of a key intermediate at the peroxy level are poorly understood. In one model, a heme-peroxy adduct [Fe a3 III OOOO(H)] is uniquely stable (2,3,(5)(6)(7)(8). This model contrasts with peroxidases (9) and catalases (10), in which the peroxy OOO bond is spontaneously cleaved to yield an oxoferryl (Fe IV AO) product and a radical. Recent Raman work on the reaction of CcO with H 2 O 2 provided an alternati...

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“…This result demonstrates that the oxo ligand of 2 does not readily exchange with H 2 18 O, in agreement with the mass spectral results described above. Related iron(IV) complexes [Fe IV (O)(TMC)(NCCH 3 )] 2ϩ and [Fe IV 2 ( -O) 2 (N,NЈ-bis(2-pyridylmethyl)-N,NЈ-dimethyl-trans-1,2-diaminocyclohexane, BPMCN) 2 ] 4ϩ are also comparably inert to exchange with solvent water (17,21), as are heme peroxidase compounds II at alkaline pH (39). In contrast, exchange of solvent water is facile for peroxidase compounds II at pH 7 because of hydrogen bonding to the oxo atom (39) and for [Fe IV (O)(porphyrin radical)] ϩ complexes via oxo-hydroxo tautomerism (40)(41)(42)(43).…”

Section: Xasmentioning

confidence: 99%