Absorption spectra of sperm-whale ferrimyoglobin

Hanania, G. I. H.; Yeghiayan, Arpi; Cameron, Bruce F.

doi:10.1042/bj1010553_b1a

Cited by 9 publications

(16 citation statements)

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“…2). This spectrum differs from those of 5‐coordinate high‐spin hemeproteins which exhibit a Soret band near ≈ 395 nm [27], and alkaline ferric hydroxide complexes of Hbs and Mbs that exhibit well defined maxima at 542 and 582 nm in the visible region [28,29].…”

Section: Resultsmentioning

confidence: 99%

Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket

Couture

Das

Savard

et al. 2000

European Journal of Biochemistry

101

130

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A putative hemoglobin (Hb) gene, related to those previously characterized in the green alga Chlamydomonas eugametos, the ciliated protozoan Paramecium caudatum, the cyanobacterium Nostoc commune and the bacterium Mycobacterium tuberculosis, was recently discovered in the complete genome sequence of the cyanobacterium Synechocystis PCC 6803. In this paper, we report the purification of Synechocystis Hb and describe some of its salient biochemical and spectroscopic properties. We show that the recombinant protein contains Fe-protoporphyrin IX and forms a very stable complex with oxygen. The oxygen dissociation rate measured, 0.011 s 21 , is among the smallest known and is four orders of magnitude smaller than the rate measured for N. commune Hb, which suggests functional differences between these Hbs. Optical and resonance Raman spectroscopic study of the structure of the heme pocket of Synechocystis Hb reveals that the heme is 6-coordinate and low-spin in both ferric and ferrous forms in the pH range 5.5±10.5. We present evidence that His46, predicted to occupy the helical position E10 based on amino-acid sequence comparison, is involved in the formation of the ferric and ferrous 6-coordinate low-spin structures. The analysis of the His46Ala mutant shows that the ferrous form is 5-coordinate and high-spin and the ferric form contains a 6-coordinate high-spin component in which the sixth ligand is most probably a water molecule. We conclude that the heme pocket of the wild type Synechocystis Hb has a unique structure that requires a histidine residue at the E10 position for the formation of its native structure. [3,6]. Despite this considerable divergence at the amino-acid sequence level, the trHbs are predicted to display a globin fold albeit with substantial residue deletions at either N-or C-terminus and in the CD±D region.Sequence comparisons show that the trHbs possess several of the key residues that are required for ligand binding in vertebrate and nonvertebrate Hbs. These include the proximal histidine at position F8 and the distal residue at position E7, which is almost invariably a histidine or glutamine. In vertebrate and nonvertebrate Hbs, the proximal histidine anchors the heme to the polypeptide chain while the distal E7 residue stabilizes oxygen through hydrogen bonding [7,8]. In a single instance, a residue (Leu) not capable of hydrogen bonding was found at the E7 position in M. tuberculosis trHb [5]. Another distal residue, at position B10, which is invariably tyrosine in trHbs, except for that of N. commune with a histidine residue, has been shown to affect ligand stability by further hydrogen bonding in the trHbs from C. eugametos [9] and M. tuberculosis [5]. A similar role has been shown for the B10 tyrosine residue in the Hb of the nematode Ascaris suum [10,11]. It is notable that C. eugametos and P. caudatum trHbs with the same B10 and E7 distal residues have very different O 2 affinities (P 50 , 0.005 mmHg and 0.6 mmHg, for C. eugametos [9] and P. caudatum [12] trHbs, respectively). This s...

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Section: Resultsmentioning

confidence: 99%

Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket

Couture

Das

Savard

et al. 2000

European Journal of Biochemistry

101

130

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“…Absorption spectra of Mb in solution have been extensively characterized (Antonini and Brunori, 1971;Hanania et al, 1966; Eaton and Hochstrasser, 1968) and are known to be rich in information concerning the physical state of the pro-tein. Mb absorption bands in the ultraviolet and visible wavelengths can be used to reveal physical properties such as the oxidation state of the heme iron (Antonini and Brunori, 1971), the identities of ligands bound to the heme (Eaton and Hochstrasser, 1968), and the structural integrity of the protein (Schechter and Epstein, 1968).…”

Section: Absorbance Of Mb In Solutionmentioning

confidence: 99%

“…In all experiments discussed in this work, the heme iron is in the ferric state. This form of Mb, often referred to as metMb, can bind various ligands from solution, including cyanide, azide, fluoride, ammonia, and formate (Hanania et al, 1966;Eaton and Hochstrasser, 1968). In the absence of specific ligands, metMb contains a water molecule or a hydroxide ion bound to the heme, depending on the pH of the solution.…”

Section: Absorbance Of Mb In Solutionmentioning

confidence: 99%

“…A few crystals of KCN were added to a diluted aliquot and the absorbance at 540 nm was measured. An extinction coefficient of 10.4 mM-1 cm-' (Hanania et al, 1966) and a Mb molecular weight of 17,800 were used for all concentration calculations. Protein solutions used in the adsorption experiments were prepared by diluting an aliquot of stock solution into PBS sparged previously with helium (as described above).…”

Section: Myoglobinmentioning

confidence: 99%

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Absorption spectra indicate conformational alteration of myoglobin adsorbed on polydimethylsiloxane

Anderson¹,

Robertson²

1995

Biophysical Journal

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To assess the effects of adsorption on protein structure, ultraviolet optical absorption spectra of myoglobin (Mb) bound to polydimethylsiloxane (PDMS) were measured. A flow cell, which enabled adsorption under controlled hydrodynamic conditions, was used in conjunction with a conventional spectrophotometer to obtain the spectra. Adsorption to PDMS reduced significantly the absorbance in the Soret region of the Mb spectrum, whereas the spectrum in the region near 280 nm was essentially unaffected. This result showed that disruption of the native structure of Mb occurs following interaction with PDMS. Furthermore, the change in the absorption spectrum may indicate loss of heme from the heme pocket of the adsorbed protein. Mb structure was altered from its solution configuration within fifteen min of contact with the surface. Exchange of adsorbed Mb with Mb in solution had little or no effect on the absorption spectrum of the surface-confined protein, indicating that exchange occurs only between conformationally altered species or between native species.

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“…The concentration of myoglobin was determined, after conversion into cyanometmyoglobin, with an extinction coefficient of 10.7 mM-' cm-' at 540 nm (Hanania et al, 1966).…”

Section: O X I D a T I O N O F M E 0 2 W I T H H 2 0mentioning

confidence: 99%

Oxidation of oxymyoglobin to metmyoglobin with hydrogen peroxide: involvement of ferryl intermediate

K¹,

Shikama²

1987

Biochemistry

118

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Hydrogen peroxide, one of the potent oxidants in muscle tissues, can induce very rapid oxidation of oxymyoglobin (MbO2) to metmyoglobin (metMb) with an apparent rate constant of 7.5 X 10(4) h-1 M-1 (i.e., 20.8 s-1 M-1) over the wide pH range of 5.5-10.2 in 0.1 M buffer at 25 degrees C. Its molecular mechanism, however, is quite different from that of the autoxidation of MbO2 to metMb. Kinetic analysis has revealed that the hydrogen peroxide oxidation proceeds through the formation of ferryl-Mb(IV) from deoxy-Mb(II), which is in equilibrium with MbO2, by a two-equivalent oxidation with H2O2. Once the ferryl species is formed, it reacts rapidly with another deoxy-Mb(II) in a bimolecular fashion so as to yield 2 mol of metMb(III). Under physiological conditions, the rate-determining step was the oxidation of the deoxy species by H2O2, its rate constant being estimated to be on the order of 3.6 X 10(3) s-1 M-1 at 25 degrees C. These findings leads us to the view that a good supply of dioxygen provides rather an important defense against the oxidation of myoglobin with hydrogen peroxide in cardiac and skeletal muscle tissues.

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Absorption spectra of sperm-whale ferrimyoglobin

Cited by 9 publications

References 0 publications

Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket

Structural investigations of the hemoglobin of the cyanobacterium Synechocystis PCC6803 reveal a unique distal heme pocket

Absorption spectra indicate conformational alteration of myoglobin adsorbed on polydimethylsiloxane

Oxidation of oxymyoglobin to metmyoglobin with hydrogen peroxide: involvement of ferryl intermediate

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