Electron transfer complex

The P450BM3 electron transfer complex structure also is consistent with mutagenesis and 

Another recent advance in P450 electron transfer is the solution of both the putidaredoxin (Pdx) and putidaredoxin reductase (Pdr) crystal structures. Thus, the structure of all components of the P450cam monooxygenase system now are known. The Pdx and Pdr structures are 

Although the structures of the various electron transfer complexes in the P450cam system are not 

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Ramirez B E, Malmstrom B G, Winkler J R and Gray H B 1995 The currents of life the terminal electron-transfer complex of respiration Proc. Natl Acad. Sc/., USA 92 11 949-51... 

The solubility of iodine in many organic vapors behaves similarly at moderate pressures, but at pressures below atmospheric the concentration of iodine is much less than in the pure saturated vapor. Jepson and Rowlinson38 suggested that this is due to strong absorption of the vapors on the surface of the iodine. The effect is most marked with vapors of substances such as pyridine which are known to form strong electron-transfer complexes with iodine. 

Kita, K. (1992) Electron-transfer complexes of mitochondria in Ascaris suum. Parasitology Today 8,155—159. 

Preparation of mixed-metal hemoglobin hybrids is achieved by separation of hemoglobin into its constituent a and P chains, followed by demetallation of one of the chains, reconstitution with MP, and chain recombination, yielding the tetrameric [a2(MP), P2(Fe P)] or [a2(Fe P), P2(MP)] species [11]. Thus, MP FeP electron transfer might in principle occur between aj/Pj or ai/P2 subunits. However, the distance between aj and Pj hemes is over 10 A greater than the and P2. This extra distance is expected, and indeed is found, to reduce ET rates by several orders of magnitude. Hence, for all practical purposes we may treat the a2P2 tetramer in terms of two independent [otj, P2] electron transfer complexes. 

Electron transfer was considered to occur at the intersection region S of the potential energy hypersurface and precursor (before electron transfer) and successor (after electron transfer) complexes, respectively. Both energy surfaces were evaluated using the potential function that was built up with an ab initio method. For each configuration, the parameter A = - Hpp was calculated. This parameter was used as... 

Dorr and Buttgereit (1963), using U.V. measurements of solutions of mesitylene and hexamethylbenzene in chloroform, bromoform, carbon tetrachloride and carbon tetrabromide, were able to demonstrate a weak electron transfer complex formation with these solvents. These investigations show that hexamethylbenzene is a more powerful electron donor than mesitylene. A similar influence on an acceptor property... 

Figure 9.7 The sequence of electron transfer complexes in the electron transfer chain. The regions enclosed by broken lines indicate the association of cam ers in complexes. Their constituents are listed in Table 9.4. Note that electrons may enter at the level of ubiquinone from sources other than succinate. Complex V is FoFi ATPase (Table 9.4).

Formation of an intimate ([cation-radical]-radical) pair, [ArH V N02] This pair is, essentially, a single-electron transfer complex, indicative of one-electron oxidation of an aromatic compound by nitronium. 

There is additional evidence that the electron-transfer complexes are not connected in fixed chains. If most of the cytochrome oxidase complexes in the membrane are inhibited with CO, the few molecules that remain uninhibited are still able to catalyze oxidation of all the cytochrome c by 02. This suggests that cytochrome c can diffuse from one cytochrome oxidase complex to another, rather than remaining bound to an individual complex. Also, cytochrome c, UQ, and the complexes themselves move about at different rates, which means that they cannot all stay stuck together. 

The only kinetic study on a V nitrogenase [74] reports that the rates of binding of the reduced Fe protein with the VFe protein and the subsequent electron-transfer rates are very similar to those for Mo nitrogenase, as the components of the V nitrogenase form a slightly weaker electron-transfer complex. 

MO studies of aromatic nitration cast doubt on the existence of jt-complexes and electron-transfer complexes in liquid-phase nitrations.14 The enthalpy of protonation of aromatic substrates provides a very good index of substrate reactivity to nitration. Coulomb interaction between electrophile and substituent can be a special factor influencing regioselectivity. A detailed DFT study of the reaction of toluene with the nitronium ion has been reported.15 Calculated IR spectra for the Wheland intermediates suggest a classical SE2 mechanism. MO calculations of cationic localization energies for the interaction of monosubstituted benzenes with the nitronium ion correlate with observed product yields.16... 

Voznesensky AI, Schenkman JB. The cytochrome P450 2B4-NADPH cytochrome P450 reductase electron transfer complex is not formed by charge-pairing. J Biol Chem 1992 267(21) 14669-14676. 

Sevrioukova IF, Li H, Zhang H, et al. Structure of a cytochrome P450-redox partner electron-transfer complex. Proc Natl Acad Sci U S A 1999 96 1863-1868. 

Inui H, Ono K, Miyatake K, Nakano Y, Kitaoka S (1987) Purification and characterization of pyruvate NADP+ oxidoreductase in Euglena gracilis. J Biol Chem 262 9130- 9135 Kita K, Takamiya S (2002) Electron-transfer complexes in Ascaris mitochondria. Adv Parasitol 51 95-131... 

Fig. 9. (A) Free-energy dependence of the second- the formation product (/

Complexes I 20) and II (68) are unstable with respect to internal electron transfer, and the rates of the thermal reactions have been measured complex III (2e) is stable with respect to electron transfer. Complex IV is symmetrical and presumably subject to rapid internal transfer (103). Optical charge transfer has not been detected in any of these systems. In the case of the two cobalt(III) complexes, comparison with the data of Table III suggests that the bands should be... 

Fig. 6. Electron transfer complex between methylamine dehydrogenase and amicyanin from Paracoccus dentrificans (PDB Accession Code 2MTA). The distance shown is between eN of the redox cofactor tryptophan tryptophylquinone of methylamine dehydrogenase and the eN of the His-95 ligand of amicyanin.

Sevrioukova, I. F., Li, H., Zhang, H., Peterson, J. A., and Poulos, T. L., 1999, Structure of a cytochrome P450-redox partaer electron-transfer complex Proc. Natl. Acad. Sci. U. S. A. 96 1863nl868. 

The struetures of eight flavoprotein electron transfer complexes will be examined (Table 1). Four of these involve flavin to heme electron transfer, three involve electron transfer between flavin and an iron-sulfur center and one involves flavin to flavin electron transfer. These eomplexes provide a variety of domain types and arrangements, cofactor types and interdomain interaetions that can help define the factors important for the electron... 

Electron donors and acceptors for the eight flavin-containing electron transfer complexes discussed. In the case of fiimarate reductase, the electron donor and acceptor indicated in the table are for the reverse of the physiological reaction catalyzed... 

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