Hemoproteins chemistry

Wood, J.M., Brown, D. G. The Chemistry of Vitamin Bj2-Enzymes. Vol. 11, pp. 47-105. Wuthrich, K. Structural Studies of Hemes and Hemoproteins by Nuclear Magnetic Resonance Spectroscopy. Vol. 8, pp. 53-121. 

Lu, A.Y. and Coon, M.J. (1968) Role of hemoprotein P-450 in fatty acid omega-hydroxylation in a soluble enzyme system from liver microsomes. Journal of Biological Chemistry, 243 (6), 1331-1332. 

Omura, T. and Sato, R. (1964) The carbon monoxide-binding pigment of liver microsomes. I. Evidence for its hemoprotein nature. Journal of Biological Chemistry, 239, 2370-2378. 

Professor Mahy received his Ph.D. in 1990 from the University of Paris 6 on a bioinorganic subject dealing with the importance of the complexes with an Fe—N bond in the chemistry of iron-porphyrin and hemoproteins. 

The above mechanistic interpretation is in contrast with the one appearing in the coordination chemistry of NO on the very labile Fe(III) porphyrins and hemoproteins, which show water substitution-controlled kinetics at the iron(III) center (22,25). The latter Fe(III) moieties are, however, high-spin systems, whilst the cyano-complexes are low-spin. There is strong experimental evidence to support the dissociative mechanism with the Fe(III)-porphyrins, because the rates are of the same order as the water-exchange reactions measured in these systems (22d). Besides, the Fe(III) centers are less oxidizing than [Fein(CN)5H20]2- (21,25). 

One of the most significant common aspects of the chemistry of NO and peroxynitrite is their ability to react in a unique manner with the metal centers of numerous proteins, in particular hemoproteins [10]. We have used myoglobin (Mb) and hemoglobin (Hb) to investigate the diverse reactions that these simple inorganic biomolecules can undergo with different oxidation states of hemoproteins. Mutated forms of Mb and Hb are available [12, 13], and a large number of transition metals ions other than Fe ions have been successfully incorporated in these... 

Matsuo T, Murata D, Hisaeda Y, Hori H, Hayashi T (2007) Porphyrinoid chemistry in hemoprotein matrix detection and reactivities of iron(IV)-oxo species of porphycene incorporated into horseradish peroxidase. J Am Chem Soc 129 12906-12907... 

Work on the redox chemistry of iron porphyrins and their protein adducts deals mainly with two problems, namely the electron transfer, which is mediated by the FeII/Fe111 couple in cytochromes, and the partial reduction of the oxygen molecule to the superoxide anion or to a peroxo bridge between two iron porphyrins. The work on isolated iron porphyrins will be summarized in this section, whereas the hemoproteins will be covered in Section VI. 

The biological implications and the redox chemistry involved in the reaction of oxygen with hemoproteins will be discussed in Section VI. Here only simple model systems which can reversible add oxygen will be briefly described. 

Interestingly, when the macrocyclic structure of porphyrin was first proposed by Kuster in 1912, nobody believed him, least of all Hans Fischer (the father of modern porphyrin chemistry), because such a large ring was thought to be intrinsically unstable. Fischer eventually came round to this structure when he and his Munich school of chemists finally succeeded in synthesising heme—the iron porphyrin in hemoproteins—from pyrrolic starting materials, in 1929. 

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