Kinetics of carbon monoxide and oxygen binding for eight electrophoretic components of sperm-whale myoglobin

Lagow, Joyce B.; Parkhurst, Lawrence J.

doi:10.1021/bi00774a014

Cited by 34 publications

(9 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been realized for some time that urea increases the pK values of dissociable groups and the measured pH of aqueous solutions, presumably by reducing the activity of hydrogen ions (12), and the fact that urea also increases the apparent pH of carrier ampholyte solutions and thus the measured pI in isoelectric focusing has been discussed by several investigators ( 2 3 , 3 5 , 4 0 , 44,45). Although the degree of elevation of pH will depend on the urea concentration and the buffering system, our studies and the reports in the literature ( Figures 1, 2 , and 3 of this rcport, our measured pI for this protein, using three different pH gradients, agrees well with the expected valucs based on reports in the literature (25,28,(31)(32)(33)(34)(35). Concerning the most cationic proteins in serum, the true pI's of these protcins havc not bcen realized, primarily because of the heretofore persistent problems in alkaline range isoelectric focusing in polyacrylamide gels (43,48).…”

Section: Discussionsupporting

confidence: 89%

“…We base this conclusion on the pI's of a specific marker protein (sperm whale myoglobin) and-the most cationic serum proteins (those with the highest PI'S). Several investigations on isoelect~ic focusing of sperm whale myoglobin have demonstrated a pI of 8.1 + 0.1 for the major component of this protein in the ferric state (25,28,(31)(32)(33)(34)(35). We also have obtained this value for our preparation of sperm whale myoglobin when it was focused in the absence of urea.…”

Section: Discussionsupporting

confidence: 60%

See 1 more Smart Citation

Electrophoretic Analysis of Serum Proteins in Cystic Fibrosis

1977

Pediatr Res

View full text Add to dashboard Cite

Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 60%

Electrophoretic Analysis of Serum Proteins in Cystic Fibrosis

1977

Pediatr Res

View full text Add to dashboard Cite

“…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

View full text Add to dashboard Cite

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...

show abstract

“…Photolysis experiments were carried out with a Phase-R 2100 BXH dye laser with rhodamine 6G as the lasing dye. A Nova 2/10 minicomputer with 32K of memory was used for data acquisition (LaGow & Parkhurst, 1972). Association of oxygen and carbon monoxide and dissociation of oxygen were measured by laser photolysis.…”

Section: Methodsmentioning

confidence: 99%