Chromatium HiPIP

Chloroxytrifluoromethane, 26 137-139 reactions, 26 140-143 addition to alkenes, 26 145-146 oxidative addition, 26 141-145 vibrational spectra, 26 139 Chloryl cation, 18 356-359 internal force constants of, 18 359 molecular structure of, 18 358, 359 properties of, 18 357, 358 synthesis of, 18 357, 358 vibrational spectra of, 18 358, 359 Chloryl compounds, reactions of, 5 61 Chloryl fluoride, 18 347-356 chemical properties of, 18 353-356 fluoride complexes of, 5 59 molecular structure of, 18 349-352 physical properties of, 18 352, 353 preparation, 5 55-57 and reactions, 27 176 properties of, 5 48 reactions, 5 58-61, 18 356 synthesis of, 18 347-349 thermal decomposition of, 18 354, 355 vapor pressures, 5 57, 18 353 vibrational spectra of, 18 349-352 Chloryl ion, 9 277 Cholegobin, 46 529 Cholesterol, astatination, 31 7 Cholorofluorphosphine, 13 378-380 h CHjPRj complexes, osmium, 37 274 Chromatium, HiPIP sequence, 38 249 Chromatium vinosum HiPIP, 38 108, 133 Fe4S4 + core, 33 60 Chromato complexes, osmium, 37 287... 

The bacterial ferredoxins from Peptococcus, Clostridium (Fig. 16-16B),267/268 Desulfovibrio, and other anaerobes each contain two Fe4S4 clusters with essentially the same structure as that of the Chromatium HIPIP.267 269 Each cluster can accept one electron. 

Here the charges shown are those on the cluster. The cysteine ligands from the protein each add an additional negative charge. The Chromatium HIPIP and the... 

High-potential Iron Proteins. These proteins (HiPIP s) have redox potentials some 0.7 V more positive than those of the ferredoxins. Chromatium HiPIP, the best characterized one, has a molecular weight of about 10,000, contains four iron atoms, four atoms of inorganic sulfur and four cysteine residues. X-ray investigation34 has shown that the iron and sulfur atoms form the tetrahedral array (Fig. 25-E-3). 

Fe(CN)6] -Chromatium HiPIP Rps Gelatinosa HiPIP Thiocapsa HiPIP Paracoccus HiPIP Chromatium HiPIP Chromatium HiPIP C. pasteurianum Fdox red C. pasteurianum Fdred red C. pasteurianum Fdred red C. pasteurianum Fdred red C. pasteurianum Fdred red ... 

Fig. 2. H NMR spectra of (A) oxidized spinach Fe2S2 ferredoxin (33) (B) reduced spinach Fe2S2 ferredoxin (5f) (C) oxidized Desulfovibrio gigas Fe3S4 ferredoxin (138) (D) oxidized ectothiorhodospira halophila HiPIP iso-II (23) (E) reduced Chromatium vinosum HiPIP (14) (F) fully reduced Clostridium pasteurianum 2(Fe4S4) ferredoxin (139). Chemical shift values are in ppm.

The heterogeneous character of the EPR spectra given by some HIPIP is probably due to the heterogeneous location of the mixed-valence pair in the [4Fe-4S] centers, which was established in detailed NMR studies (121, 122). Since a heterogeneous location of the mixed-valence pair was also observed in the case of the [4Fe-4S] centers of Chromatium vinosum ferredoxin (123), the same phenomenon may account for the complex EPR spectra displayed by these centers in some proteins (124-126). 

The spin-lattice relaxation rate of Chromatium vinosum HIPIP was measured between 5 and 50 K (103). In comparison with the [4Fe-4S] cluster of B. stearothermophilus ferredoxin, the relaxation was found to be faster below 15 K and slower above this temperature. 

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. 

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.)...

Figure 25 X-Ray structure of the active sites of the 4Fe proteins (a) HiPIP Chromatium vinosum (b) Bacillus thermoproteolyticus...

Fig. 6. View of the Fe4S4 and a5Ru(His42) centers in Chromatium vinosum HIPIP. The edge-edge distance is 7.9 A [38]...

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... 

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.

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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