Metmyoglobin-cyanide

Reduction of the metmyoglobin-cyanide complex by sodium dithionite... 

Four spin-labelled derivatives of sperm whale metmyoglobin were prepared by site-directed mutagenesis.101 Cyanide anion or imidazole was added to prepare low-spin Fe(III). Iron relaxation rates were measured by saturation recovery or inversion recovery between 5 and 17 K and by analysis of the temperature-dependent contribution to the CW line widths of the iron signal at 20 to 160 K. The nitroxyl 7i values in spin-labelled Zn-substituted myoglobin were measured to provide values in the absence of interaction with the more rapidly-relaxing Fe(III). The full shapes of the nitroxyl saturation-recovery curves for the spin-... 

The Mechanism of Nitrite Ion Binding to Metmyoglobin Under some physiological conditions, NO can be rapidly metabolized to nitrogen species in the + 3 (NO2 ) and + 5 (NO, ) oxidation states.319 It is of chemical and biological interest to establish the similarities or differences of the interaction of NO and the nitrite ion with metMb. Earlier kinetics and thermodynamics studies of these reactions were undertaken but no firm mechanistic conclusions were reached.320 Two anionic ligands, azide and cyanide, exhibit different reactivities toward metMb, and... 

The spectra of ferric porphyrins are much more complex than those of the "typical metalloporphyrins discussed in Section II. Fig. 6 shows the spectra of metmyoglobin (MbH20) and ferrimyoglobin cyanide (MbCN). The latter is seen to have a fairly typical metalloporphyrin spectrum, although the a-band is rather weak and there is a new, weak band in the near infra-red. The spectrum of MbH20 is completely different the bands between 17 kK and 19 kK are similar in position to the a- and /3-bands of the cyanide, but there are new bands at around 10 kK, 16 kK, and 20 kK. 

Steinhaus, R.K., Baskin, S.I., Clark, J.H., Kirby, S.D. (1990). Formation of methemoglobin and metmyoglobin using 8-aminoquinoline derivatives or sodium nitrite and subsequent reaction with cyanide. J. Appl. Toxicol. 10 345-51. 

Figure 6 Background-subtracted cyclic voltammetry of metmyoglobin (A) 86 J,M met-myoglobin, pH 7.0 (B) 67 mM metmyoglobin, pH 7.0, with excess cyanide to give [Mb(III)Hp] [CN-] of 1 300. Scan rates 20, 50, 100, 200 mV/s.

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