A chemometric analysis of the resonance Raman spectra of mutant carbonmonoxy-myoglobins reveals the effects of polarity

Anderton, Clare L.; Hester, R. E.; Moore, John N.

doi:10.1016/s0167-4838(96)00194-x

Cited by 47 publications

(67 citation statements)

References 30 publications

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“…Empirical calculations using point negative charges predict that such a bond order relation would hold, and the Fe-CO bond order is expected to decrease because of the negative charge (44). This effect was confirmed in a Mb mutant (His(E7)Val/Val(E11)Thr) in which the Fe-CO stretching mode shifted from ϳ510 cm Ϫ1 in the wild-type protein to 478 cm Ϫ1 in the mutant (45,47). This was attributed to the interaction of the CO with the hydroxyl oxygen atom of the threonine.…”

Section: Discussionmentioning

confidence: 86%

“…A linear correlation is seen between the bending and stretching modes. Resolving and assigning the Fe-C-O bending mode is not straightforward when there are multiple CO conformers present (35,45) or when there are spectroscopic complexities such as Fermi resonance coupling of the bending mode (e.g. wild-type myoglobin shows a doublet at 576 and 585 cm Ϫ1 ; Ref.…”

Section: Discussionmentioning

confidence: 99%

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Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Das

Dewilde

Friedman

et al. 2006

Journal of Biological Chemistry

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Sequence alignment of hemoglobins of the trematodes Paramphistomum epiclitum and Gastrothylax crumenifer with myoglobin suggests the presence of an unusual active site structure in which two tyrosine residues occupy the E7 and B10 helical positions. In the crystal structure of P. epiclitum hemoglobin, such an E7-B10 tyrosine pair at the putative helical positions has been observed, although the E7 Tyr is displaced toward CD region of the polypeptide. Resonance Raman data on both P. epiclitum and G. crumenifer hemoglobins show that interactions of heme-bound ligands with neighboring amino acid residues are unusual. Multiple conformers in the CO complex, termed the C, O, and N conformers, are observed. The conformers are separated by a large difference (ϳ60 cm ؊1 ) in the frequencies of their Fe-CO stretching modes. In the C conformer the Fe-CO stretching frequency is very high, 539 and 535 cm ؊1 , for the P. epiclitum and G. crumenifer hemoglobins, respectively. The Fe-CO stretching of the N conformer appears at an unusually low frequency, 479 and 476 cm ؊1 , respectively, for the two globins. A population of an O conformer is seen in both hemoglobins, at 496 and 492 cm ؊1 , respectively. The C conformer is stabilized by a strong polar interaction of the CO with the distal B10 tyrosine residue. The O conformer is similar to the ones typically seen in mutant myoglobins in which there are no strong interactions between the CO and residues in the distal pocket. The N conformer possesses an unusual configuration in which a negatively charged group, assigned as the oxygen atom of the B10 Tyr side chain, interacts with the CO. In this conformer, the B10 Tyr assumes an alternative conformation consistent with one of the conformers seen the crystal structure. Implications of the multiple configurations on the ligand kinetics are discussed.It is now well recognized that hemoglobins (Hbs) 3 are widespread in all phyla. There has been a renewed interest in understanding the structure and function of Hbs in recent years (1-5), because these Hbs are located in diverse cellular compartments and possess atypical physicochemical properties. Hbs have been discovered in about 33% of the animal species, and in addition to being present in vertebrates, they are found in the phyla that include nematode, mollusc, and annelid, to name but a few. Single subunit globins have been discovered lately in algae, nonsymbiotic plants, and a number of prokaryotes ranging from bacteria to cyanobacteria (see Refs. 2-5). Additionally, flavoproteinbound chimeric Hbs have been found in bacteria (6) and yeast (7). In most cases, the nonvertebrate Hbs are proposed to have dissimilar functions from those in vertebrate Hbs; the latter class is established as consisting of O 2 carrier proteins. However, additional cellular activities have been proposed recently for vertebrate Hbs as well (8).Although the nonvertebrate Hbs bind O 2 and other ligands just as the vertebrate Hbs, the kinetic and structural properties of the O 2 complexes (see for example Refs...

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Das

Dewilde

Friedman

et al. 2006

Journal of Biological Chemistry

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“…The red shifting of the CO stretching frequency of Ht-M61A/Q64N relative to Ht-M61A is reminiscent of the IR spectrum of aqueous MbCO, which exhibits three primary CO stretching peaks corresponding to three structurally distinct conformational substates. 39,51,56,[62][63][64][65][66] The A 0 band (1965 cm -1 ) is attributed to a conformation in which the distal histidine (His64) is positioned out of the heme pocket, 51,[67][68][69][70][71] while the A 1 (1944 cm -1 ) and A 3 (1938 cm -1 ) bands arise from the distal histidine being localized in the heme pocket in two distinct orientational geometries. 39,72 In the case of MbCO, the inclusion of a polar, hydrogen-bond-donating residue inside the heme pocket results in a spectral shift of the CO stretch to lower frequencies.…”

Section: Resultsmentioning

confidence: 99%

Cytochrome c₅₅₂Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy

et al. 2006

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Spectrally resolved infrared stimulated vibrational echo experiments are used to measure the vibrational dephasing of a CO ligand bound to the heme cofactor in two mutated forms of the cytochrome c 552 from Hydrogenobacter thermophilus. The first mutant (Ht-M61A) is characterized by a single mutation of Met61 to an Ala (Ht-M61A), while the second variant is doubly modified to have Gln64 replaced by an Asn in addition to the M61A mutation (Ht-M61A/Q64N). Multidimensional NMR experiments determined that the geometry of residue 64 in the two mutants is consistent with a non-hydrogen-bonding and hydrogen-bonding interaction with the CO ligand for Ht-M61A and Ht-M61A/Q64N, respectively. The vibrational echo experiments reveal that the shortest time scale vibrational dephasing of the CO is faster in the Ht-M61A/ Q64N mutant than that in Ht-M61A. Longer time scale dynamics, measured as spectral diffusion, are unchanged by the Q64N modification. Frequency-frequency correlation functions (FFCFs) of the CO are extracted from the vibrational echo data to confirm that the dynamical difference induced by the Q64N mutation is primarily an increase in the fast (hundreds of femtoseconds) frequency fluctuations, while the slower (tens of picoseconds) dynamics are nearly unaffected. We conclude that the faster dynamics in Ht-M61A/Q64N are due to the location of Asn64, which is a hydrogen bond donor, above the heme-bound CO. A similar difference in CO ligand dynamics has been observed in the comparison of the CO derivative of myoglobin (MbCO) and its H64V variant, which is caused by the difference in axial residue interactions with the CO ligand. The results suggest a general trend for rapid ligand vibrational dynamics in the presence of a hydrogen bond donor.

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“…An extensive series of myoglobin variants with distal pocket mutations [2,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], form the most comprehensive available set ot mFeC/mCO data (Table 1) at constant trans ligation; these data are plotted in Fig. 1 and form the canonical Mb line, against which other adducts can be compared.…”

Section: The Mfec Vs Mco Backbonding Correlationsmentioning

confidence: 99%

CO as a vibrational probe of heme protein active sites

Spiro

Wasbotten

2005

Journal of Inorganic Biochemistry

206

343

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A chemometric analysis of the resonance Raman spectra of mutant carbonmonoxy-myoglobins reveals the effects of polarity

Cited by 47 publications

References 30 publications

Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Cytochrome c₅₅₂Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy

CO as a vibrational probe of heme protein active sites

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A chemometric analysis of the resonance Raman spectra of mutant carbonmonoxy-myoglobins reveals the effects of polarity

Cited by 47 publications

References 30 publications

Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Multiple Active Site Conformers in the Carbon Monoxide Complexes of Trematode Hemoglobins

Cytochrome c552Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy

CO as a vibrational probe of heme protein active sites

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Cytochrome c₅₅₂Mutants: Structure and Dynamics at the Active Site Probed by Multidimensional NMR and Vibration Echo Spectroscopy