Determination of the amounts and oxidation states of hemoglobins M Boston and M Saskatoon in single erythrocytes by infrared microspectroscopy.

Dong, Aichun; Nagai, Masako; Yoneyama, Yoshimasa; Caughey, Winslow S.

doi:10.1016/s0021-9258(18)47257-2

Cited by 6 publications

(5 citation statements)

References 31 publications

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“…Furthermore, the reduction potential of the heme iron (−550 mV) is the lowest reported for the iron(III)/iron(II) pair of a heme protein . This is consistent with the high exposure of heme to the solvent and with the presence of a tyrosinate as the axial ligand, known to decrease the redox potential of the bound metal ion. − As observed in many heme proteins, two heme orientations rotated by 180° around the α−γ meso axis are present. − …”

Section: Introductionsupporting

confidence: 66%

“…19 This is consistent with the high exposure of heme to the solvent and with the presence of a tyrosinate as the axial ligand, known to decrease the redox potential of the bound metal ion. [20][21][22] As observed in many heme proteins, two heme orientations rotated by 180°around the R-γ meso axis are present. [23][24][25] Tyrosine is an unusual ligand in heme proteins.…”

Section: Introductionmentioning

confidence: 84%

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Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA

et al. 2005

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Hemophore HasA is a 19 kDa iron(III) hemoprotein that participates in the shuttling of heme to a specific membrane receptor. In HasA, heme iron has an original coordination environment with a His/Tyr pair as axial ligands. Recently developed two-dimensional protonless (13)C-detected experiments provide the sequence-specific assignment of all but three protein residues in the close proximity of the paramagnetic center, thus overcoming limitations due to the short relaxation times induced by the presence of the iron(III) center. Mono-dimensional (13)C and (15)N experiments tailored for the detection of paramagnetic signals allow the identification of resonances of the axial ligands. These experiments are used to characterize the conformational features and the electronic structure of the heme iron(III) environment. The good complementarity among (1)H-, (13)C-, and (15)N-detected experiments is highlighted. A thermal high-spin/low-spin equilibrium is observed and is related to a modulation of the strength of the coordination bond between the iron and the Tyr74 axial ligand. The key role of a neighboring residue, His82, for the stability of the axial coordination and its involvement in the heme delivery to the receptor is discussed.

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Section: Introductionsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 84%

Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA

et al. 2005

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“…When oxygen binds to the abnormal R subunit, rapid oxidation of heme iron and the subsequent formation of the Fe(III)-tyrosinate bond must proceed as illustrated in Figure 12. In the previous paper, we showed the presence of the reduced abnormal subunits in patient's blood with Hb M Saskatoon and Hb M Boston by EPR (49) and IR (50). This is another evidence supporting the scheme of Figure 12.…”

Section: Discussionsupporting

confidence: 77%

Heme Structure of Hemoglobin M Iwate [α87(F8)His→Tyr]: A UV and Visible Resonance Raman Study

Nagai

Aki

et al. 2000

Biochemistry

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Heme structures of a natural mutant hemoglobin (Hb), Hb M Iwate [alpha87(F8)His-->Tyr], and protonation of its F8-Tyr were examined with the 244-nm excited UV resonance Raman (UVRR) and the 406.7- and 441.6-nm excited visible resonance Raman (RR) spectroscopy. It was clarified from the UVRR bands at 1605 and 1166 cm(-)(1) characteristic of tyrosinate that the tyrosine (F8) of the abnormal subunit in Hb M Iwate adopts a deprotonated form. UV Raman bands of other Tyr residues indicated that the protein takes the T-quaternary structure even in the met form. Although both hemes of alpha and beta subunits in metHb A take a six-coordinate (6c) high-spin structure, the 406.7-nm excited RR spectrum of metHb M Iwate indicated that the abnormal alpha subunit adopts a 5c high-spin structure. The present results and our previous observation of the nu(Fe)(-)(O(tyrosine)) Raman band [Nagai et al. (1989) Biochemistry 28, 2418-2422] have proved that F8-tyrosinate is covalently bound to Fe(III) heme in the alpha subunit of Hb M Iwate. As a result, peripheral groups of porphyrin ring, especially the vinyl and the propionate side chains, were so strongly influenced that the RR spectrum in the low-frequency region excited at 406.7 nm is distinctly changed from the normal pattern. When Hb M Iwate was fully reduced, the characteristic UVRR bands of tyrosinate disappeared and the Raman bands of tyrosine at 1620 (Y8a), 1207 (Y7a), and 1177 cm(-)(1) (Y9a) increased in intensity. Coordination of distal His(E7) to the Fe(II) heme in the reduced alpha subunit of Hb M Iwate was proved by the observation of the nu(Fe)(-)(His) RR band in the 441.6-nm excited RR spectrum at the same frequency as that of its isolated alpha chain. The effects of the distal-His coordination on the heme appeared as a distortion of the peripheral groups of heme. A possible mechanism for the formation of a Fe(III)-tyrosinate bond in Hb M Iwate is discussed.

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“…These replacements in Hb M's Iwate, Boston, and Hyde Park make the redox potential of the heme iron more negative, so that the oxidized heme becomes toughly resistant to reduction by erythrocyte methemoglobin reductases even under anaerobic conditions and is retained in the ferric state in blood (4). Although the abnormal metsubunit of Hb M Saskatoon can be reduced by the methemoglobin reductases under anaerobic conditions at the same rate as metHb A, their autoxidation rates are so fast that some of the abnormal met-subunit still remains in the ferric state in blood (4)(5)(6). In a previous study (7), we demonstrated by 488.0-nm excited resonance Raman (RR) spectroscopy that only the heme iron of abnormal β subunit of Hb M Saskatoon adopts the hexacoordinate high-spin structure in contrast to the pentacoordinate high-spin structure in Hb M's Iwate, Boston, and Hyde Park.…”

mentioning

confidence: 99%

Heme Structures of Five Variants of Hemoglobin M Probed by Resonance Raman Spectroscopy

Jin

Nagai

et al. 2004

Biochemistry

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The alpha-abnormal hemoglobin (Hb) M variants show physiological properties different from the beta-abnormal Hb M variants, that is, extremely low oxygen affinity of the normal subunit and extraordinary resistance to both enzymatic and chemical reduction of the abnormal met-subunit. To get insight into the contribution of heme structures to these differences among Hb M's, we examined the 406.7-nm excited resonance Raman (RR) spectra of five Hb M's in the frequency region from 1700 to 200 cm(-1). In the high-frequency region, profound differences between met-alpha and met-beta abnormal subunits were observed for the in-plane skeletal modes (the nu(C=C), nu(37), nu(2), nu(11), and nu(38) bands), probably reflecting different distortions of heme structure caused by the out-of-plane displacement of the heme iron due to tyrosine coordination. Below 900 cm(-1), Hb M Iwate [alpha(F8)His --> Tyr] exhibited a distinct spectral pattern for nu(15), gamma(11), delta(C(beta)C(a)C(b))(2,4), and delta(C(beta)C(c)C(d))(6,7) compared to that of Hb M Boston [alpha(E7)His --> Tyr], although both heme irons are coordinated by Tyr. The beta-abnormal Hb M variants, namely, Hb M Hyde Park [beta(F8)His --> Tyr], Hb M Saskatoon [beta(E7)His --> Tyr], and Hb M Milwaukee [beta(E11)Val --> Glu], displayed RR band patterns similar to that of metHb A, but with some minor individual differences. The RR bands characteristic of the met-subunits of Hb M's totally disappeared by chemical reduction, and the ferrous heme of abnormal subunits was no longer bonded with Tyr or Glu. They were bonded to the distal (E7) or proximal (F8) His, and this was confirmed by the presence of the nu(Fe-His) mode at 215 cm(-1) in the 441.6-nm excited RR spectra. A possible involvement of heme distortion in differences of reducibility of abnormal subunits and oxygen affinity of normal subunits is discussed.

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Determination of the amounts and oxidation states of hemoglobins M Boston and M Saskatoon in single erythrocytes by infrared microspectroscopy.

Cited by 6 publications

References 31 publications

Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA

Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA

Heme Structure of Hemoglobin M Iwate [α87(F8)His→Tyr]: A UV and Visible Resonance Raman Study

Heme Structures of Five Variants of Hemoglobin M Probed by Resonance Raman Spectroscopy

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Determination of the amounts and oxidation states of hemoglobins M Boston and M Saskatoon in single erythrocytes by infrared microspectroscopy.

Cited by 6 publications

References 31 publications

Direct-Detected13C NMR to Investigate the Iron(III) Hemophore HasA

Direct-Detected13C NMR to Investigate the Iron(III) Hemophore HasA

Heme Structure of Hemoglobin M Iwate [α87(F8)His→Tyr]: A UV and Visible Resonance Raman Study

Heme Structures of Five Variants of Hemoglobin M Probed by Resonance Raman Spectroscopy

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Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA

Direct-Detected¹³C NMR to Investigate the Iron(III) Hemophore HasA