The effects of amino acid substitution at position E7 (residue 64) on the kinetics of ligand binding to sperm whale myoglobin.

Rohlfs, Ronald J.; Mathews, Antony J.; Carver, Theodore E.; Olson, John S.; Springer, Barry A.; Egeberg, Karen D.; Sligar, Stephen G.

doi:10.1016/s0021-9258(19)39749-2

Cited by 279 publications

(176 citation statements)

References 41 publications

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“…The unusually high values of k off(CO) for CO dissociation from Mt-Nb(II)-CO and Hs-Nb(II)-CO, as derived from linear plots of k obs(CO) versus [CO] ( Figure 3C), are closely similar with those directly measured following CO displacement by NO ( Figure 4). The values of k off(CO) are~140-fold higher than that reported for At-Nb(II)-CO decarbonylation [29] and~500-fold higher than those observed in mammalian Mbs (e.g., Pc-Mb(II)) [15]. The resulting values of the dissociation equilibrium constant for CO binding to Mt-Nb(II) and Hs-Nb(II) (i.e., k off(CO) /k on(CO) ) are very high, being 6.3 × 10 -5 M and 3.8 × 10 −5 M, respectively.…”

Section: Heme-proteincontrasting

confidence: 57%

“…The resulting values of the dissociation equilibrium constant for CO binding to Mt-Nb(II) and Hs-Nb(II) (i.e., k off(CO) /k on(CO) ) are very high, being 6.3 × 10 -5 M and 3.8 × 10 −5 M, respectively. These values are about 200-fold and 1000-fold higher than those of At-Nb(II) (2.2 × 10 −7 M) [29] and mammalian Mbs (e.g., Ec-Mb(II), 5.7 × 10 −8 M; and Pc-Mb(II), 3.7 × 10 −8 M) [15,52].…”

Section: Heme-proteinmentioning

confidence: 75%

“…The low reactivity of CO for Mt-Nb(II) and Hs-Nb(II) ( Figure 3), as compared to that for Pc-Mb(II) [15] (Table 1), may be ascribed either to (i) proximal effects, possibly related to a higher activation free energy for the in-plane motion of the Fe-His proximal bond [56] and/or to (ii) distal effects, due to either the steric hindrance exerted by the heme distal residues (His85 in Mt-Nb and Thr91 in Hs-Nb), altering the Fe(II)-C-O angle [57] and/or crowding of H 2 O molecules in the vicinity of the heme because of the exposure of the distal side to the bulk solvent. The unusually high CO dissociation rate constant from Mt-Nb(II)-CO ( Figure 4) indeed may reflect a weakening of the heme-Fe-His proximal bond for the carbonylated species, as suggested by the unusual ν(Fe-C)/ν(CO) position ( Figure 1C).…”

Section: Heme-proteinmentioning

confidence: 97%

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Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

Masi

Pesce

et al. 2021

IJMS

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Structural and functional properties of ferrous Mycobacterium tuberculosis (Mt-Nb) and human (Hs-Nb) nitrobindins (Nbs) were investigated. At pH 7.0 and 25.0 °C, the unliganded Fe(II) species is penta-coordinated and unlike most other hemoproteins no pH-dependence of its coordination was detected over the pH range between 2.2 and 7.0. Further, despite a very open distal side of the heme pocket (as also indicated by the vanishingly small geminate recombination of CO for both Nbs), which exposes the heme pocket to the bulk solvent, their reactivity toward ligands, such as CO and NO, is significantly slower than in most hemoproteins, envisaging either a proximal barrier for ligand binding and/or crowding of H2O molecules in the distal side of the heme pocket which impairs ligand binding to the heme Fe-atom. On the other hand, liganded species display already at pH 7.0 and 25 °C a severe weakening (in the case of CO) and a cleavage (in the case of NO) of the proximal Fe-His bond, suggesting that the ligand-linked movement of the Fe(II) atom onto the heme plane brings about a marked lengthening of the proximal Fe-imidazole bond, eventually leading to its rupture. This structural evidence is accompanied by a marked enhancement of both ligands dissociation rate constants. As a whole, these data clearly indicate that structural–functional relationships in Nbs strongly differ from what observed in mammalian and truncated hemoproteins, suggesting that Nbs play a functional role clearly distinct from other eukaryotic and prokaryotic hemoproteins.

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Section: Heme-proteincontrasting

confidence: 57%

Section: Heme-proteinmentioning

confidence: 75%

Section: Heme-proteinmentioning

confidence: 97%

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Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

Masi

Pesce

et al. 2021

IJMS

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“…Considerable insight has been gained by the characterization of the ligand-binding properties of myoglobin variants in which His-64 has been replaced (reviewed in [9]). From this work it is now known that the replacement of His-64 with non-polar residues (valine, leucine, phenylalanine and isoleucine) leads to pentaco-ordinated ferric haem proteins lacking a distally coordinated water molecule [10][11][12][13][14][15][16]. The loss of this bound water molecule is primarily attributable to two factors : (1) the additional hydrophobicity of the non-polar residues introduced at position 64, and (2) the disruption of the stabilizing hydrogen bond between the distal histidine residue and the co-ordinated water molecule.…”

Section: Introductionmentioning

confidence: 99%

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

Maurus

Bogumil

Nguyen

et al. 1998

Biochemical Journal

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The high-resolution X-ray crystallographic structures of horse heart azidometmyoglobin complexes of the wild-type protein and the His-64-->Thr variant have been determined to 2.0 and 1.8 A respectively. Azide binds to wild-type metmyoglobin in a bent configuration with an Fe-N-1-N-3 angle of 119 degrees and is oriented into the distal crevice in the direction of Ile-107. The proximity of the His-64 NE2 atom to the N-1 atom of the bound azide indicates stabilization of the ligand by the His-64 side chain through hydrogen bonding. In addition, structural characterization of wild-type horse heart azidometmyoglobin establishes that the only structural change induced by ligand binding is a small movement of the Leu-29 side chain away from the azide ligand. EPR and Fourier transform infrared spectroscopy were used to characterize the myoglobin azide complexes further. EPR spectroscopy revealed that, in contrast with wild-type azidometmyoglobin, two slightly different low-spin species are formed by azide bound to the His-64-->Thr variant both in solution and in a polycrystalline sample. One of these low-spin species has a greater relative intensity, with g values very similar to those of the azide complex of the wild-type protein. These EPR results together with structural information on this variant indicate the presence of two distinct conformations of bound azide, with one form predominating. The major conformation is comparable to that formed by wild-type myoglobin in which azide is oriented into the distal crevice. In the minor conformation the azide is oriented towards the exterior of the protein.

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“…A water molecule hydrogen-bonded to the N ⑀ of the distal histidine is known to lower the diffusive ligand association rate constant in equilibrium deoxyMb (Carver et al, 1990;Smerdon et al, 1991). The Scheme 2 analysis does not show modulation of the geminate association rate constant, but the hydrogen-bonded water molecule is thought to lower the diffusive on rate in Mb by hindering ligand entrance to the pocket (Rohlfs et al, 1990), through the histidine gate mechanism proposed by Perutz (1989) and by steric crowding of the heme pocket. By microscopic reversibility, similar mechanisms may also lower the escape rate constant of the geminate ligand from the pocket after a water molecule enters the heme pocket and associates with the distal histidine.…”

mentioning

confidence: 96%

Multiple Geminate Ligand Recombinations in Human Hemoglobin

Esquerra

Goldbeck

Reaney

et al. 2000

Biophysical Journal

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The geminate ligand recombination reactions of photolyzed carbonmonoxyhemoglobin were studied in a nanosecond double-excitation-pulse time-resolved absorption experiment. The second laser pulse, delayed by intervals as long as 400 ns after the first, provided a measure of the geminate kinetics by rephotolyzing ligands that have recombined during the delay time. The peak-to-trough magnitude of the Soret band photolysis difference spectrum measured as a function of the delay between excitation pulses showed that the room temperature kinetics of geminate recombination in adult human hemoglobin are best described by two exponential processes, with lifetimes of 36 and 162 ns. The relative amounts of bimolecular recombination to T- and R-state hemoglobins and the temperature dependence of the submicrosecond kinetics between 283 and 323 K are also consistent with biexponential kinetics for geminate recombination. These results are discussed in terms of two models: geminate recombination kinetics modulated by concurrent protein relaxation and heterogeneous kinetics arising from alpha and beta chain differences.

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The effects of amino acid substitution at position E7 (residue 64) on the kinetics of ligand binding to sperm whale myoglobin.

Cited by 279 publications

References 41 publications

Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

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

Multiple Geminate Ligand Recombinations in Human Hemoglobin

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