Kinetic and equilibrium studies of the ligand binding reactions of eight electrophoretic components of sperm whale ferrimyoglobin

Parkhurst, Lawrence J.; Lagow, Joyce B.

doi:10.1021/bi00677a016

Cited by 9 publications

(3 citation statements)

References 19 publications

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“…Although it is known that sperm whale myoglobin consists of a number of components separable by isoelectric focussing [27], these appear to be essentially identical in their reactions with ligands [8]. In addition there was no kinetic evidence for any heterogeneity in the reactions studied here: in particular time courses such as those of Fig.…”

Section: Methodsmentioning

confidence: 63%

The Reduction by Dithionite of Fe(III) Myoglobin Derivatives with Different Ligands Attached to the Iron Atom

Cox

Hollaway

1977

European Journal of Biochemistry

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1. The reductions of a number of sperm whale Fe(II1) myoglobin-ligand complexes by sodium dithionite in a phosphate buffer pH 6.4, were investigated by using rapid-wavelength-scanning stopped-flow spectrophotometry. The ligands were azide, cyanide, fluoride, imidazole, thiocyanate and water.2. The reduction of Fe(II1) myoglobin cyanide led to the transient formation of Fe(I1) myoglobin cyanide but no intermediate species were observable during the reductions of the other derivatives. The final product of the reaction in all cases was unliganded Fe(I1) myoglobin.3 . Investigation of the effect of dithionite concentration on the rate of reduction indicated that the SO;-radical ion was the active species in reducing the azide, cyanide, fluoride and thiocyanate derivatives.4. Comparison of the observed rates of reduction at different ligand concentrations with those predicted for a pathway of reduction involving prior dissociation of the ligand, allowed us to estimate the rate of reduction with the ligand in position (outer-sphere reduction). There was a large variation in the relative rates of outer-sphere reduction in the order imidazole % CN-> SCN-$ N, + F-.The fluoride derivative was so resistant to outer-sphere reduction that the reaction with SO;-proceeded only by a pathway involving dissociation of F-before reduction. It was calculated that any direct reduction of this complex was at least 100 times slower than that of the azide derivative.5. The results are discussed in terms of the possible r81e of the axial ligands in haem proteins and it is suggested that the pathway of the electron to the Fe(II1) centre may be via the pn orbitals of these ligands.Several decades ago, Balthazard and Phillipe [l] observed that the reduction of the Fe(II1) haemoglobin cyanide complex by dithionite involved the transient formation of a species considered to be Fe(I1) haemoglobin cyanide. This observation implies an electron transfer from the reductant to the iron centre without direct contact. It is not unreasonable to suppose that Fe(II1) myoglobin cyanide undergoes a similar reaction.As it is possible to make a number of other liganded Fe(II1) myoglobin complexes [2], it seemed that a study of their reduction by dithionite would provide a useful model system for investigating the effect of ligands on the redox properties of iron in a haem protein. This would have obvious relevance to the understanding of the electron transfer properties of cytochromes, in which both non-haem ligands are usually provided by the protein. In addition we hoped Abbreviation. Mb, myoglobin. to record the spectra of previously unknown Fe(I1) myoglobin complexes which might occur as transient intermediates, c j Fe(I1) myoglobin cyanide. We have chosen to carry out such a study with Fe(II1) myoglobin derivatives to avoid complications which could arise from haem-haem interaction in haemoglobin.The present experiments were greatly facilitated by the use of a rapid-wavelength-scanning stoppedflow spectrophotometer, described previously [3]. This...

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Section: Methodsmentioning

confidence: 63%

The Reduction by Dithionite of Fe(III) Myoglobin Derivatives with Different Ligands Attached to the Iron Atom

Cox

Hollaway

1977

European Journal of Biochemistry

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“…For example, the harbor seal myoglobin shows identity with the Amazon River dolphin myoglobin at positions 122 and 129 , and other identities are given in Figure 6. It should be noted that all these comparisons are made in terms of the main component of myoglo-bin from skeletal muscle of the given species (Garner et al, 1974;Parkhurst and LaGow, 1975). The yield of minor myoglobin components from the Amazon River dolphin appeared relatively sparse.…”

Section: Discussionmentioning

confidence: 99%

Coordination complexes and catalytic properties of proteins and related substances. 72. Complete amino acid sequence of the major component myoglobin of Amazon River dolphin (Inia geoffrensis)

Dwulet¹,

Bogardt²,

Jones³

et al. 1975

Biochemistry

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The complete amino acid sequence of the major component myoglobin from Amazon River dolphin, Inia geoffrensis, was determined by specific cleavage of the protein to obtain large peptides which are readily degraded by the automatic sequencer. Three easily separable peptides were obtained by cleaving the protein with cyanogen bromide at the methionine residues and four peptides were obtained by cleaving the methyl-acetimidated protein with trypsin at the arginine residues. From these peptides over 85% of the sequence was completed. The remainder of the sequence was obtained by fragmentation of the large cyanogen bromide peptide with trypsin. This protein differs from that of the common porpoise, Phocoena phocoena, at seven positions, from that of the common dolphin, Delphinus delphis, at 11 positions, and from that of the sperm whale, Physeter catodon, at 15 positions. By comparison of this sequence with the three-dimensional structure of sperm whale myoglobin it appears that those residues close to the heme group are most conserved followed by those in nonhelical regions and lastly by those in the helical segments. All of the substitutions observed in this sequence fit easily into the three-dimensional structure of the sperm whale myoglobin.

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“…Firstly, electrophoresis or IEF of homogeneous preparations of ferric Mb often yield many fractions with identical amino acid compositions, ligand kinetics and conformations, but different charges (e.g. Rumen, 1959;Edmundson & Hirs, 1962;Atassi, 1964;Parkhurst & LaGow, 1975;Wittenberg & Wittenberg, 1981). Yet, these fractions are not artefacts of the isolation procedure or proteolysis in the muscle homogenates (Wittenberg & Wittenberg, 1981).…”

Section: Discussionmentioning

confidence: 99%

Radular myoglobin and protein variation within and among some littorinid species (Mollusca: Gastropoda)

Medeiros

Serpa

Brito

et al. 1998

Aspects of Littorinid Biology

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The radular muscles of several littorinid species, including Littorina littorea, L. saxatilis, L. obtusata, L. striata and Melarhaphe neritoides, contain myoglobin (Mb). Here we report on the presence of radular Mb in eight other littorinids: L. compressa, L. arcana, L. fabalis, Nodilittorina punctata, N. trochoides, N. radiata, Littoraria undulata and Littoraria cingulifera. Using native polyacrylamide gel electrophoresis (PAGE) and isoelectric focusing (IEF) we compared the Mb and soluble protein (SP) profiles of these species. This suggested that: (1) L. saxatilis and L. arcana may have specific Mb/SP profiles, (2) Littoraria spp., Nodilittorina spp. and L. striata share similar Mb patterns, (3) Mb is remarkably diverse in the genus Littorina, (4) L. littorea shows intraspecific Mb/SP variation, (5) L. saxatilis does not show geographic Mb/SP differences, and (6) IEF uncovers substantial hidden Mb/SP heterogeneity not shown by PAGE (particularly for Melarhaphe neritoides). Hence, littorinid Mb/SP may be a useful taxonomic marker whose ecophysiological significance deserves further study, even if its genetic basis remains unclear.

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Kinetic and equilibrium studies of the ligand binding reactions of eight electrophoretic components of sperm whale ferrimyoglobin

Cited by 9 publications

References 19 publications

The Reduction by Dithionite of Fe(III) Myoglobin Derivatives with Different Ligands Attached to the Iron Atom

The Reduction by Dithionite of Fe(III) Myoglobin Derivatives with Different Ligands Attached to the Iron Atom

Coordination complexes and catalytic properties of proteins and related substances. 72. Complete amino acid sequence of the major component myoglobin of Amazon River dolphin (Inia geoffrensis)

Radular myoglobin and protein variation within and among some littorinid species (Mollusca: Gastropoda)

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