Effect of complexation between cobinamides and bovine serum albumin on their reactivity toward cyanide

High Reactivity of Supermolecular Nanoentities of a Vitamin B12 Derivative in Langmuir–Schaefer Films Toward Gaseous Toxins

“…Addition of NH 3 gas to SMEs of (CN – ) Bu Cby in LS films results in the formation of species with maxima in the UV–vis spectrum at 361 and 553 nm (Figure ). This spectrum is close to the UV–vis spectra of hydroxocyano species or amino complexes of monocyano incomplete corrinoids (e.g., cobinamide, heptamethyl cobyrinate, and others). Incubation of the (CN – ) Bu Cby LS film after the reaction with NH 3 under vacuum, in an argon flow, or in the air for a prolonged time (up to 2 weeks) results in its almost negligible regeneration (Figure S17).…”

“…When formation conditions are altered, monolayers (Figure 2B) and bilayers (Figure 2A) can be produced on the water surface under the same surface pressures. Eight samples of different thicknesses were prepared from edge-on monolayers, i.e., 10,20,30,40,50,70, 90, and 110 monolayers, which approximately corresponds to the film thicknesses 20, 40, 60, 80, 100, 140, 180, and 220 nm, respectively.…”

“…However, the reaction between H 2 OCbl and CN – has some features that can decrease its efficacy as an antidote, i.e., it is relatively slow in neutral aqueous solutions, and H 2 OCbl forms complexes with biological ligands and proteins , that leads to inhibition of the CN – binding. In contrast to H 2 OCbl, cobinamides (Cbis), nucleotide-free derivatives of Cbls, react with CN – significantly more rapidly, and some Cbi species retain this reactivity in the presence of competitive ligands. , Moreover, Cbis possesses higher water solubility and can be introduced via intramuscular injection . These facts explain the higher efficacy of Cbis as a cyanide antidote in comparison with H 2 OCbl. − In contrast to H 2 OCbl, Cbis have been successfully employed as hydrogen sulfide antidotes as well. − The reaction between aquahydroxocobinamide and H 2 S proceeds more rapidly than that involving H 2 OCbl and results in the reduction of Co­(III) ion to Co­(II) and its sulfur-containing species (viz., Co­(II)-S • – and Co­(II)-SSH •2– ) via the transient generation of Co­(III)-hydrosulfido complexes.…”

“…In contrast to H 2 OCbl, cobinamides (Cbis), nucleotide-free derivatives of Cbls, react with CN − significantly more rapidly, and some Cbi species retain this reactivity in the presence of competitive ligands. 7,10 Moreover, Cbis possesses higher water solubility and can be introduced via intramuscular injection. 11 These facts explain the higher efficacy of Cbis as a cyanide antidote in comparison with H 2 OCbl.…”