Chromatium high-potential protein

High-potential protein from Chromatium vinosum (Fe3+/Fe2+) 0.11... 

Adman, E. T., Watenpaugh, K. D., and Jensen, L. H. (1975). NH---S hydrogen bonds in Peptococcus aerogenes ferrodoxin, Clostridium pasteurianum rubredoxin and Chromatium high potential iron protein. Proc. Natl. Acad. Sci. U.S.A. 72,4854—4858. 

Freer, S. T., Alden, R. A., Carter, C. W., Jr., and Kraut, J. (1975). Crystallographic structure refinement of Chromatium high potential iron protein at two angstroms resolution. /. Biol. Chem. 250, 46-54. 

The functions of the heme is uncertain. The soluble mammalian succinate dehydrogenase resembles closely that of E. coli and contains three Fe-S centers binuclear SI of E° 0 V, and tetranuclear S2 and S3 of -0.25 to -0.40 and + 0.065 V, respectively. Center S3 appears to operate between the -2 and -1 states of Eq. 16-17 just as does the cluster in the Chromatium high potential iron protein. The function of the very low potential S2 is not certain, but the following sequence of electron transport involving SI and S3 and the bound ubiquinone QD-S66 has been proposed (Eq. 18-4). 

Figure 17. Schematic diagrams of some representative topologically chiral proteins.79 (a) Condensed schematic drawing of the L subunit of the quinoprotein TV-MADH. The looped line represents the polypeptide backbone with N and C terminals. Cysteine (or half-cystine) residues are numbered, and their a-carbons are indicated by filled circles. Intrachain disulfide bonds are shown as dashed lines joining a pair of filled circles. The heavy line symbolizes an intrachain cofactor link, (b) Chromatium high potential iron protein (HiPIP), one of several Fe4S4 cluster-containing proteins, (c) Toxin II from the scorpion Androctonus australis Hector. Reprinted with permission from C. Liang and K. Mislow, J. Math. Chem. 1994,15,245. Copyright 1994, Baltzer Science Publishers.

Adrenodoxin Chromatium high potential iron protein Spinach ferredoxin Cl. pasteurianum ferredoxin... 

Chromatium high potential non-heme iron protein (S) 350 1... 

Mossbauer spectroscopy of Fe-enriched MoFe protein in dithionite-reduced and dye-oxidized oxidation states were interpreted in terms of approximately 50% of the Fe in the protein being present in cubane clusters similar to [4Fe-4S] clusters of simpler Fe-S proteins, e.g., ferredoxins and Chromatium high-potential iron proteins. Spectra of MoFe protein in which P clusters were selectively enriched with Fe were consistent with two of the clusters having slightly different environments. 

Scattering-Density Maps of Chromatium High-Potential Iron Protein, J. Mol. Biol. (1968) 35, 503. 

The two species represented in equation 29.13 do not actually possess localized Fe(ll) and Fe(III) centres, rather the electrons are delocaUzed over the cluster core. One could envisage further oxidation to species that are formally 3Fe(III) Fe(II) and 4Fe(III). Whereas the latter is never accessed under physiological conditions, 3Fe(III)-Fe(II) is the oxidized form of HIPIP (high-potential protein), i.e. 2Fe(III) 2Fe(II) is the reduced form of HIPIP or the oxidized form of ferredoxin. In contrast to the reduction potentials of ferredoxins, those of HIPIPs are positive, e.g. -1-360 mV for HIPIP isolated from the bacterium Chromatium vinosum. 

While the oxidation reduction potential of the ferredoxins is —0.2 V to —0.4 V and that of the rubredoxins is about —0.05 V, a protein from the photosynthetic bacterium Chromatium has a redox potential of +0.35 V. This is the high potential iron protein, or HIPIP. 

Rate constants for the oxidation of the negatively charge high potential Fe/S protein from Chromatium Vinosum with PCu(II) do not exhibit any dependence on pH 5.0 - 8.5 which suggests that the His 87 site is being used in this case. 

Figure 6.4 Absorption spectrum (A) and CD spectrum (B) of the [Fe4S4] cluster of a high-potential iron protein (HiPIP) from Chromatium sp. (From Cowan, 1997. Reproduced with permission from John Wiley Sons., Inc.)...

Several models have been proposed for the active center of iron and sulphur in Clostridial ferredoxin in which the cysteine residues in the peptide chain participate in the sulphur bridging. Fig 9 166). Unfortunately X-ray analysis of crystals of these proteins has not been completed. It is difficult to confirm that all the irons are clustered in a single linear array 167, 168). X-ray studies of another non-heme iron protein, the high potential iron protein, hipip, from chromatium, carried out by J. Kraut (personal communication), indicate that the four irons of this molecule may be clustered in a tetrahedral array. 

Another group of related electron carriers, the high-potential iron proteins (HIPIP) contain four labile sulfur and four iron atoms per peptide chain 261-266 X-ray studies showed that the 86-residue polypeptide chain of the HIPIP of Chromatium is wrapped around a single iron-sulfur cluster which contains the side chains of four cysteine residues plus the four iron and four sulfur atoms (Fig. 16-15D)261 This kind of cluster is referred to as [4Fe-4S], or as Fe4S4. Each cysteine sulfur is attached to one atom of Fe, with the four iron atoms forming an irregular tetrahedron with an Fe-Fe... 

Dus, K., H. De Klerk, K. Sletten, and R. G. Bartsh Chemical characterization of high potential iron proteins from chromatium and rhodopseudomonas gelati-nosa. Biochim. Biophys. Acta 140, 291 (1967). 

High potential iron sulfur protein (Chromatium)... 

The [4 Fe-4 S] cores have been one of the most intriguing inorganic structures involved in biological systems. Carter et al. (1977) 191 demonstrated that the same basic structure is present in the two [4 Fe—4 S] centers of the 8 Fe ferredoxin of Peptococcus aerogenes (E 0 = - 400 mV)2) and in the high potential iron protein (HiPIP) isolated from the purple photosynthetic bacterium Chromatium vinosum... 

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