Carbonyl-hemoglobin

Considering that LEH is still in a developmental phase, it is imperative that each batch of LEH is fully characterized for physicochemical and biological properties. Typically, lipid content, particle diameter, oxygen affinity, hemoglobin, methemoglobin, carbonyl-hemoglobin, oncotic pressure, viscosity, endotoxin, and osmolality are determined by conventional methods. Several issues that need specific attention in the case of LEH are as follows ... 

Model systems for carbonmonoxy (also called carbonyl) hemoglobin show a geometry similar to that of the Fe—C = 0 group, linear or nearly so and essentially perpendicular to the porphyrin plane. " The biochemical literature is littered with reports that this is not the geometry adopted by CO in binding to hemoglobins. We will return to this topic later in this chapter, since the physiological consequences are potentially important. 

Figure 19. Infrared spectra of oxyhemoglobin and carbonyl-hemoglobin in the region 2000-700 cm ...

HCN and nitric oxide hastened the incapacitation in rats prodnced by carbon monoxide. Such incapacitation occurred at a carbonyl hemoglobin concentration of... 

Having identified the two resonances in intact hemoglobin the authors proceeded to investigate possible differences in their chemistry. Carbon-13 NMR results clearly showed that the p heme units of normal met hemoglobin A are more readily reduced than the oc hemes. Also, when the carbonylated hemoglobin A was treated with an oxidizing agent, the NMR spectra showed that it was the oc heme unit that was more reactive. The oc hemes were, in addition, found to lose CO more readily. 

The treatment of whole blood cell suspensions with i CO, C02, and i CN" ion has been studied by C NMR (157). Dog whole blood that was carbonylated with i CO exhibited a resonance at 206.1 ppm (converted from benzene standard, 128.5 ppm) with a linewidth of 55 3 Hz. This resonance was assigned to the i CO of intracellular carbonyl hemoglobin. These results are identical to the corresponding values for carbonyl hemoglobin in hemolyzed dog blood. The C NMR spectra of human whole blood exposed to C02 shows three resonances. These were assigned to the HCOs ion, CO2, and the carbamino resonance of the C02 complex of the terminal valine residues of hemoglobin cc and P chains. The spectra of the i CN ion added to whole blood suggests that two distinct environments are occupied by the cyanide ion. 

Kohlenozyd, n, carbon monoxide, -eisen, n. iron carbonyl, -gas, n. carbon monoxide gas. -hamoglobin, n. compound of carbon monoxide with hemoglobin, -kalium, n. potassium carboxide, potassium hexacar-bonyl. -knallgas, n, explosive mixture of carbon monoxide and oxygen, -nickel, n. nickel carbonyl. 

The lethal effects of carbon monoxide on hemoglobin had been analyzed by Claude Bernard and shown to be due to the formation of an iron-carbonyl compound. In 1891 Mond and Langer showed that iron pentacarbonyl could be dissociated by light, and in 1897 J.S. Haldane and J.L. Smith found light would decompose the carbonyl compound of hemoglobin. Other metal carbonyls are not photodecomposed. 

Iron, as found in the porphyrin derivative hemoglobin, complexes CO to form a stable metal carbonyl. Iron also forms a variety of metal carbon monoxide derivatives such as the homoleptic Fe(CO)5, Fe2(CO)9 and Fe3(CO)i2, the anionic [Fe(CO)4] and its covalent derivative Fe(CO)4Br2, [CpFe(CO)2] and its alkylated covalent derivatives CpFe(CO)2-R with its readily distinguished n (and and a (and / ) iron carbon bonds. By contrast. Mg in its chlorin derivative chlorophyll, which very much resembles porphyrin, forms no such bonds with CO nor is there a rich magnesium carbonyl chemistry (if indeed, there is any at all). 

Although nickel carbonyl is intensely poisonous, it is used in the Mond process for the refinement of nickel (see Section 16.3). Complex formation is also responsible for carbon monoxide s toxicity it attaches more strongly than oxygen to the iron in hemoglobin and prevents it from accepting oxygen from the air in the lungs. As a result, the victim suffocates. 

Carbon monoxide is very toxic, rapidly giving a bright red complex with the hemoglobin of blood. Carbon monoxide reacts with alkali metals in liquid ammonia to give the alkali metal carbonyls these white solids contain the [OCCO]2 ion. 

Visible and Soret Spectral Data for Oxy and Carbonyl Complexes of Hemoglobin, Myoglobin, and Cytochrome c Oxidase... 

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