Hemoglobin complexes

Harris, G. 1966. Low spin ferric hemoglobin complexes. Theoretica Chimica Acta 5 379-397. 

Saeo, M.K., Moure, C.M., Burnett, J.C., Joshi, G.S., and Abraham, D.J. High-resolution crystal structure of deoxy hemoglobin complexed with a potent allosteric effector. Protein Sci. 2001, 10, 951-957. 

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). 

Scaloni A, Ferranti P, De Simone G et al (1999) Probing the reactivity of nucleophile residues in human 2,3-diphosphoglycerate/deoxy-hemoglobin complex by aspecific chemical modifications. FEBS Lett 452 190-194... 

Phosphorus trifluoride is a colorless gas, best made by fluorination of PC13 with AsF3 or ZnF2. It forms complexes with transition metals similar to those formed by carbon monoxide. Like CO, it is highly poisonous because of the formation of a hemoglobin complex. Unlike the other trihalides, PF3 is hydrolyzed only slowly by water, but it is attacked by alkalis. 

Carbon monoxide is poisonous because it binds to the Fe of hemoglobin more strongly than does oxygen. Hemoglobin complexed with CO cannot carry O2 from the lungs to the tissues. Without O2 in the tissues for metabolism, cells cannot function, so they die. 

Heme that is released into the blood stream by lysis of red cells, catabolism of haptoglobin-hemoglobin complexes, or other mechanisms binds to albumin (Ka = 10 M) and hemopexin (Ka 10 M) (48). The hemopexin-heme complex is taken up in the liver by a receptor-mediated process. A candidate for the hemopexin-heme receptor has been identified (49). Other heme-binding proteins are a-l-microglobulin and the glutathione transferases. 

The primary functions of Hp were initially thought to be the preservation of iron and the prevention of possible damage to the renal tubules by excreted hemoglobin. However, Hp-hemoglobin complexes and free Hp itself also play significant roles in the control of local inflammatory processes ... 

Other proposed functions for Hp or the Hp-hemoglobin complex include inhibition of nitric oxide and prostaglandin synthesis, angiogenesis, and control of lymphocyte and neutrophil function. All of these may be relevant to the control of inflammation. 

Figure 20-6 The common phenotypes of haptoglobin, as shown by sieving gel electrophoresis of haptoglobin-hemoglobin complexes.

Samples to be injected were prepared by dissolving 2.5 mg PDMDAAC per ml in the mobile phase, along with increasing amoimts of BSA. All samples were filtered (0.20 pm Millipore) before injection. Injections were performed in mobile phases of various pH, all below pHcritical- To determine the stoichiometries of polymer-protein complexes, we used the Hummel-Dreyer method (24), as recently applied to dextran sulfate-hemoglobin complexes (25). 

Fig. 11 Effect of specific inhibitors of the respiratory chain on the nitrite reductase activity of rat liver mitochondria. Mitochondria were incubated with nitrite for 2 h under argon in the presence of succinate or glutamate/malate (Glu/Mal). Nitric monoxide derived from nitrite was trapped with hemoglobin. The concentration of NO-hemoglobin complexes was measured using low temperature ESR spectroscopy. Other details are described in Kozlov et al. [46]. CON control, ROT rotenone, TTFA thenoyltrifluoroacetone, MYX myxothiazol, AA antimycin A...

A. Dapsone metabolites oxidize the ferrous iron hemoglobin complex to the ferric state, resulting in methemoglobinemia. 

Alben and Caughey also compared mass effects for free gases with those for CO-hemoglobin complexes. For example, they gave the ratio (based on experimental values)... 

To avoid bonding with other, possibly harmful molecules, several histidine molecules — an amino acid — are placed around the oxygen-binding location, that effectively guards the location. There are two histidine molecules attached to each heme group, or subunit, in a hemoglobin complex. These cause a distortion in the protein shape so that only a molecule with a nonlinear geometry can bind to it. Similar to puzzle pieces, only the atom with the correct shape and symmetry can fit comfortably. 

The atherogenic capacity of HDL can be Umited via enrichment of the lipoprotein with the enzymes group llA secretory phospholipase A2 and myeloperoxidase, and other factors such as triglycerides, ceruloplasmin, serum amyloid A, and haptoglobin-hemoglobin complex [144,145]. 

Zehl, M. andAllmaier, G. (2004) Ultraviolet matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of intact hemoglobin complex from whole human blood. 

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