Myoglobin and Hemoglobin

Line spectrum calculated in the low temperature approximation, valid at both 4 °K and 1.2 °K. There are no free parameters the lack of sharp lines in the observed spectra is attributed to spin relaxation (After Lang and Marshall, Ref. 103)) 

An excellent review of the Mossbauer spectroscopic data on hemo-proteins has been published recently by Lang (195). 

Cytochromes from bacterial, yeast, and mammalian sources have been investigated by Mossbauer spectroscopy (114—117). Horseheart cytochrome c and the c-type cytochrome from T. utilis show spectra characteristic of low-spin Fe(III) in the oxidized form of the protein and low-spin Fe(II) for the reduced form of the protein. Lang et al. (115) have analyzed the Mossbauer data in terms of a low-spin Hamiltonian in some detail. Cooke and Debrunner (116) present quadrupole data on dehydrated forms of oxidized and reduced cytochrome c the quadrupole splittings for hydrated and dehydrated forms of the reduced protein are quite similar in contrast to a difference of the oxidized form. No spin-state change is reported for either form of cytochrome c. 

Cytochromes cc and methemoglobin hydroxide have been proposed to be proteins which also exist in a thermal mixture of S =5/2 and S = 1/2 

The kinetics of the reduction of hemoglobin by Fe(III) and Cu(II) complexes indicate the presence of both simple outer-sphere and site-specific electron transfer mechanisms. With the Fe(III) chelate oxidants the pathway is dependent on the reduction potential and the stability of the Hb complex, while for Cu(II) oxidations the outer-sphere process occurs at the a subunits, with the site-specific mechanism involving metal binding at the Cys p-93 residue. 

NMR methods.The kinetics of the oxidations of Fe(II) cyt C553 from 5. obliquus and A variabilis with [Fe(CN)6] and [Co(phen)3] have been investigated and the rate constant trends compared with the corresponding reactions with plas-tocyanin PCu(I) from the same sources.  

The intracomplex electron transfer rate constants for the oxidations of S. cervisiae cytochrome 62 by native Fe(III) cyt c (600 300s, and Zn (600 200 s 0 and (H2Porph) (700 100s 0 excited state derivatives, are relatively 

Hiickel expression. The rates of electron transfer from bovine liver cyt to a series of Fe(lII) and Cu(III) chelate complexes have been measured, with prior binding of the Cu(II) species to the protein indicated from saturation kinetic behavior.  

The kinetics of the oxidations of Chromatium vinosum HIPIP by several ferrocenium derivatives show no inhibitions by charged redox-inactive metal complexes, and display a pH dependence (pK = 6.90) in which protonation reduces the HIPIP reactivity by a factor of two. Electron transfer at an uncharged hydrophobic patch near Cys-46 (4 A from the Fe4S4 core to the surface), enhanced by deprotonation of His-42, is inferred from the data. The self-exchange rate constant for the HIPIPo/HIPIPr couple is estimated to be 5 x 10 s from 

The long-range electron transfer reactions in ruthenium-modified myoglobin, in which the labile heme unit has been replaced by various metalloporphyrins, have been reviewed. The reductions of the [Ru(NH3)5] moiety, attached at His-48, by Pd- and Pt-substituted hemes in myoglobin proceed at rates of 9 1 x 1(P and 1.2x lO s , respectively. The difference in rates for electron transfer between Fe (heme) and Mg or Zn(porphyrin) centers in [a(Fe(II)P),j3(M T)] hemoglobin hybrids indicates a direct process as opposed to the involvement of a conformational gate. Using [Co(NH3)5Cl] to quench the Zn state, a rate constant of 2.4 x 10 s has been measured for back electron transfer within [a(Zn- -P)i8(Fe(III)CN)].  

Galaris, L. Eddy, A. Arduini, E. Cadenas, P. Hochstein, Biochem. 

Antonini, M. Brunori, Hemoglobin and Myoglobin in their Reactions with Ligands, Norfh-Holland, Amsterdam, 1971. 

Synthetic Approaches to Study Multivalent Carbohydrate-Lectin Interactions 

The parameter AGmultl is made up of enthalpic (AHmultl) and entropic (ASmultl) components (Eq. 1) which have to be considered separately. 

According to this discussion, AGmulti for a (theoretical) bivalent system with rigid perfectly fitting spacers is given by Eqs (2) and (3). 

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Genberg L, Richard L, McLendon G and Miller R J D 1991 Direct observation of global protein motion in hemoglobin and myoglobin on picosecond time scales Science 251 1051-6... 

The abihty of iron to exist in two stable oxidation states, ie, the ferrous, Fe ", and ferric, Fe ", states in aqueous solutions, is important to the role of iron as a biocatalyst (79) (see Iron compounds). Although the cytochromes of the electron-transport chain contain porphyrins like hemoglobin and myoglobin, the iron ions therein are involved in oxidation—reduction reactions (78). Catalase is a tetramer containing four atoms of iron peroxidase is a monomer having one atom of iron. The iron in these enzymes also undergoes oxidation and reduction (80). 

The so-called globin proteins are an important group of a-helical proteins. These include hemoglobins and myoglobins from many species. The globin structure can be viewed as two layers of helices, with one of these layers perpendicular to the other and the polypeptide chain moving back and forth between the layers. 

Special Focus Hemoglobin and Myoglobin— Paradigms of Protein Structure and Function... 

Cytochromes were first named and classified on the basis of their absorption spectra (Figure 21.9), which depend upon the structure and environment of their heme groups. The b cytochromes contain iron—protoporphyrin IX (Figure 21.10), the same heme found in hemoglobin and myoglobin. The c cytochromes contain heme c, derived from iron-protoporphyrin IX by the covalent attachment of cysteine residues from the associated protein. UQ-cyt c... 

The qualitative relationship between the oxygen binding curves for hemoglobin and myoglobin. 

Iron, Fe2+ (d6) 6, octahedral A-Imidazole, porphyrin Dioxygen transport in hemoglobin and myoglobin... 

B. Chance, S. Nioka, J. Kent, K. McCully, M. Fountain, R. Greenfeld, and G. Holtom. Time-resolved spectroscopy of hemoglobin and myoglobin in resting and ischemic muscle. Anal. Biochem., 174 698-707, 1988. 

The use of the reversion spectroscope enabled the position of the absorption bands to be determined accurately and to be conclusively distinguished from hemoglobin and myoglobin. It became clear that there were three different intracellular respiratory catalysts— cytochromes a,b,c—common to animals, bacteria, yeast and higher plants. In 1925 a preliminary scheme for the passage of O2 from blood to tissue was proposed ... 

Fermi, G. Perutz, M.F. (1981). Atlas of Molecular Structures in Biology. 2, Hemoglobin and Myoglobin. Clarendon press, Oxford. 

B. M. Bennett, S. M. Kobus, J. F. Brien, K. Nakatsu, G. S. Marks, Requirement for Reduced, Unliganded Hemoprotein for the Hemoglobin- and Myoglobin-Mediated Biotransformation of Glyceryl Trinitrate , J. Pharmacol. Exp. Ther. 1986, 237, 629-635. 

Hemoglobin and Myoglobin Alessandro Rossi Fanelli, Eraldo Antonini, and Antonio Caputo... 

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