Structural and spectroscopic studies of azide complexes of horse heart myoglobin and the His-64→Thr variant

Maurus, R.; Bogumil, Ralf; Nguyen, Nham T.; Mauk, A. Grant; Brayer, G.D.

doi:10.1042/bj3320067

Cited by 54 publications

(40 citation statements)

References 43 publications

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“…Moreover, the positive charge on N(1) is increased by the negative charge of the iron-bound nitrogen atom, N(3), which is hydrogen-bonded to the amide group of Gly-143. Taking this molecular polarization into account, an asymmetric resonance structure is dominant for the azide bound to HO-heme, as proposed previously for the myoglobin complex with azide (28). Tyr-58, Arg-136, and Asp-140 are all conserved in mammalian HO-1 and HO-2 and in Corynebacterium diphtheriae HO, indicative of their importance in the hydrogen-bonding network.…”

Section: Discussionmentioning

confidence: 76%

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Crystal Structure of Rat Heme Oxygenase-1 in Complex with Heme Bound to Azide

Sugishima¹,

Sakamoto²,

Higashimoto³

et al. 2002

Journal of Biological Chemistry

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Heme oxygenase (HO) catalyzes physiological heme degradation consisting of three sequential oxidation steps that use dioxygen molecules and reducing equivalents. We determined the crystal structure of rat HO-1 in complex with heme and azide (HO-heme-N 3 ؊ ) at 1.9-Å resolution. The azide, whose terminal nitrogen atom is coordinated to the ferric heme iron, is situated nearly parallel to the heme plane, and its other end is directed toward the ␣-meso position of the heme. Based on resonance Raman spectroscopic analysis of HO-heme bound to dioxygen, this parallel coordination mode suggests that the azide is an analog of dioxygen. The azide is surrounded by residues of the distal F-helix with only the direction to the ␣-meso carbon being open. This indicates that regiospecific oxygenation of the heme is primarily caused by the steric constraint between the dioxygen bound to heme and the F-helix. The azide interacts with Asp-140, Arg-136, and Thr-135 through a hydrogen bond network involving five water molecules on the distal side of the heme. This network, also present in HO-heme, may function in dioxygen activation in the first hydroxylation step. From the orientation of azide in HO-heme-N 3 ؊ , the dioxygen or hydroperoxide bound to HO-heme, the active oxygen species of the first reaction, is inferred to have a similar orientation suitable for a direct attack on the ␣-meso carbon.

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Section: Discussionmentioning

confidence: 76%

“…On the addition of azide to HO-heme, low spin shift of the Soret band in the optical spectrum occurs (19,27), indicative that azide coordinates to the ferric heme iron. In the case of myoglobin, azide is bound parallel to the heme plane as dioxygen (28). The binding mode of azide provides a model of dioxygen (hydroperoxide) binding to HO-heme.…”

mentioning

confidence: 99%

Crystal Structure of Rat Heme Oxygenase-1 in Complex with Heme Bound to Azide

Sugishima¹,

Sakamoto²,

Higashimoto³

et al. 2002

Journal of Biological Chemistry

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“…Mb molecule was taken from its crystallographic data and assumed to be 10 nm 2 [44]. It was shown that a full monolayer coverage corresponds to 10 17 molecules/m 2 (or 1.66 x 10 -11 mol cm -2 ).…”

Section: Cyclic Voltammetry Of Myoglobinmentioning

confidence: 99%

Electrochemical behaviour of myoglobin at an array of microscopic liquid–liquid interfaces

O'Sullivan

Arrigan

2012

Electrochimica Acta

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Electrochemistry at liquid-liquid interfaces, or at interfaces between two immiscible electrolyte solutions (ITIES), provides a basis for the non-redox detection of biological molecules, based on iontransfer or adsorption processes. The electroactivity of myoglobin at an array of micron-sized liquidorganogel interfaces was investigated. The µITIES array was patterned with a silicon membrane consisting of an array of eight pores with radii of ~12.8 µm and a pore to pore separation of ~400 µm.Using cyclic voltammetry at the ITIES, the protein was shown to adsorb at the interface and facilitate the transfer of the organic phase electrolyte anions to the aqueous side of the interface. The electrochemical current response was linear with concentration in the range of 1 -6 µM, with corresponding surface coverage of 10 -50 pmol cm -2 . The reverse peak currents was found to be proportional to the voltammetric scan rate, indicating a desorption process. The detection of the protein was only possibly when the pH of the aqueous phase solution was below the pI of the protein. The steady-state simple ion transfer behaviour of tetraethylammonium cation was decreased on the forward sweep, providing a qualitative indication of the presence of adsorbed protein at the interface.Increasing the ionic strength of the aqueous phase resulted in enhanced peak currents, possibly due to aggregation of protein precipitates in the aqueous solution. UV/Vis absorbance spectroscopy was used 1 ISE Member.2 | P a g e to investigate the effects of various aqueous electrolyte solutions on the structure of the protein, and it was shown that at low pH the protein is at least partially denatured. These results provide the basis for label-free detection of myoglobin at the ITIES.

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“…These two classes of compounds were investigated because of their intense infrared transitions and ideal frequencies (see Table 3). The azide ion has already been used in infrared studies as a ligand bound to the heme iron of myoglobin (28). The successful incorporation of organic azides into proteins by the Tirrell lab (29) suggests that this vibration might be used as a general probe in proteins.…”

Section: Nitrilesmentioning

confidence: 99%

Vibrational Stark Effects Calibrate the Sensitivity of Vibrational Probes for Electric Fields in Proteins

2003

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Infrared spectroscopy is widely used to probe local environments and dynamics in proteins. The introduction of a unique vibration at a specific site of a protein or more complex assembly offers many advantages over observing the spectra of an unmodified protein. We have previously shown that infrared frequency shifts in proteins can arise from differences in the local electric field at the probe vibration. Thus, vibrational frequencies can be used to map electric fields in proteins at many sites or to measure the change in electric field due to a perturbation. The Stark tuning rate gives the sensitivity of a vibrational frequency to an electric field, and for it to be useful, the Stark tuning rate should be as large as possible. Vibrational Stark effect spectroscopy provides a direct measurement of the Stark tuning rate and allows a quantitative interpretation of frequency shifts. We present vibrational Stark spectra of several bond types, extending our work on nitriles and carbonyls and characterizing four additional bond types (carbon-fluorine, carbon-deuterium, azide, and nitro bonds) that are potential probes for electric fields in proteins. The measured Stark tuning rates, peak positions, and extinction coefficients provide the primary information needed to design amino acid analogues or labels to act as probes of local environments in proteins.The application of infrared spectroscopy to protein structure and dynamics has largely focused on the intense amide modes of the protein backbone. These modes, the strongest of which have been classified amide I, amide II, and amide III, are sensitive to secondary contacts, have relatively large intensities, and have been used to estimate secondary structure (1), monitor protein fluctuations (2), and observe conformational changes upon ligand binding (3) or during folding (4). The main disadvantage of the amide vibrations is that they arise from bonds throughout the protein and provide no information about local environments. It has been shown that 13 C labeling of specific amide carbonyls can provide site-specific amide I transitions (5), but the modest isotopic frequency shift (∼37 cm -1

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Structural and spectroscopic studies of azide complexes of horse heart myoglobin and the His-64→Thr variant

Cited by 54 publications

References 43 publications

Crystal Structure of Rat Heme Oxygenase-1 in Complex with Heme Bound to Azide

Crystal Structure of Rat Heme Oxygenase-1 in Complex with Heme Bound to Azide

Electrochemical behaviour of myoglobin at an array of microscopic liquid–liquid interfaces

Vibrational Stark Effects Calibrate the Sensitivity of Vibrational Probes for Electric Fields in Proteins

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