Cytochrome complex with

Raag, R. and Poulos, T. L. (1991) Crystal structures of cytochrome complexed with camphane, thiocamphor and adamantane factors controlling P450 substrate hydroxylation. Biochemistry 30, 2674-2684. 

Organosulfur Compounds. These compounds, Hsted in Table 8, are used in a variety of appHcations, including cooling water, paint, and metalworking. Methylenebisthiocyanate hydroly2es rapidly at a pH above 8 to cyanate ion which complexes with ferric iron to poison the cytochrome systems (36). 

Another important group of cytochromes, found in plants, bacteria and animals is cytochrome P-450, so-called because of the absorption at 450 nm characteristic of their complexes with CO. Their function is to activate... 

Cyanides are strong Lewis bases that form a range of complexes with d-block metal ions. They are also famous as poisons. When they are ingested, they combine with certain protein molecules—the cytochromes—involved in the transfer of electrons and the supply of energy in cells, and the victim dies. 

Ostermeier C, Harrenga A, Ermler U, Michel H. 1997. Structure at 2.7 A resolution of the Paracoccus denitrificans two-subunit cytochrome c oxidase complexed with an antibody Ev fragment. Proc Natl Acad Sci USA 94 10547. 

Alston, K., Robinson, R.C., Park, S.S., Gelboin, H.V., and Friedman, F.K. (1991) Interactions among cytochromes P-450 in the endoplasmic reticulum. Detection of chemically cross-linked complexes with monoclonal antibodies./. Biol. Chem. 266, 735-739. 

Recently, a ternary complex of cytochrome c with a polyanionic /1-cyclodextrin has been reported (85). A self-assembled supra-molecular bidentate N,P ligand for aqueous organometallic catalysis was also described (86). Although related, such systems are out of the scope of this review and will not be discussed further here. 

In order to obtain further information on the magnitude of the overall reaction volume and the location of the transition state along the reaction coordinate, a series of intermolecular electron-transfer reactions of cytochrome c with pentaammineruthenium complexes were studied, where the sixth ligand on the ruthenium complex was selected in such a way that the overall driving force was low enough so that the reaction kinetics could be studied in both directions (153, 154). The selected substituents were isonicotinamide (isn), 4-ethylpyr-idine (etpy), pyridine (py), and 3,5-lutidine (lut). The overall reaction can be formulated as... 

Similar results were obtained for the redox reactions of a series of cobalt diimine complexes with cytochrome c (156, 157). In general a good agreement exists between the kinetically and thermodynami-... 

The cytochrome he complex in eukaryotes is a homodimeric, multi-subunit entity (Figure 13.13a). Each monomer has three catalytic subunits a cytochrome b, with two b-type haems, one Rieske ISP containing a [2Fe-2S] cluster and one cytochrome c, with... 

Wester, M.R., Johnson, E.F., Marques-Soares, C., Dijols, S., Dansette, P.M., Mansuy, D. and Stout, C.D. (2003) Structure of mammalian cytochrome P450 2C5 complexed with diclofenac at 2.1 A resolution evidence for an induced fit model of substrate binding. Biochemistry, 42, 9335-9345. 

Scott, E.E., White, M.A., He, Y.A., Johnson, E.F., Stout, C.D. and Halpert, J. R. (2004) Structure of mammalian cytochrome P450 2B4 complexed with 4-(4-chlorophenyl) imidazole at 1.9-A resolution insight into the range of P450 conformations and the coordination of redox partner binding. The Journal... 

Zhao, Y., White, M.A., Muralidhara, B.K., Sun, L., Halpert, J.R. and Stout, C.D. (2006) Structure of microsomal cytochrome P450 2B4 complexed with the antifungal drug bifonazole insight into P450 conformational plasticity and membrane interaction. The Journal of Biological Chemistry, 281, 5973-5981. 

Yano, J.K., Hsu, M.H., Griffin, K.J., Stout, C.D. and Johnson, E.F. (2005) Structures of human microsomal cytochrome P450 2A6 complexed with coumarin and mefhoxsalen. Nature Structural Molecular Biology, 12, 822-823. 

Porphyrins 21 are the backbone of major players in life cycles—cytochromes (Scheme 8). There are three types of cytochromes, classified by their color, or more precisely by their long-wavelength absorption band, as a (600 mn), b (563 nm), and c (550 nm). They are protein conjugates of a porphyrin complex with iron(II), which is a coenzyme called heme (22). In plants, porphyrins form a complex with magnesium-(II) chlorophylls a and b (23), vital in photosynthesis. Porphyrin derivatives are used in photodynamic therapy for dermatological diseases such as psoriasis, and for skin or subcutaneous cancer.5c-e... 

Multiple forms of cytochrome P-1+50. It is now clear that there are more than one form of cytochrome P-1+50. Thomas et al. have recently shown by immunochemical means that there are at least six forms of mammalian cytochrome P-1+50 (39) In 1960 s it was noted that there are at least two catalytically and spectrally distinct cytochrome P-l+50 s, viz. cytochrome P-1+50 and cytochrome P-1+1+8 or P -1+50 (1 0, 1 1). Cytochrome P-1+1+8 is inducible by PAH s such as 3-methylcholanthrene (MC) and BP. It metabolizes preferentially PAH s (such as the above carcinogenic inducers). Cytochrome P-1+1+8 derives its name from the fact that when reduced and complexed with carbon monoxide it has an absorbance maximum at 1+1+8 nm. Cytochrome P-1+50 induced by compounds such as phenobarbital (PB) appears similar to the control cytochrome P-1+50 both spectrally and catalytically. 

Cardiolipin forms also tight complexes, with the adenine nucleotide translocator (ATM) affecting its translocator activity (Beyer and Nuscher, 1996). Six cardiohpin residues are tightly bound to lysines (Beyer and Klingenberg, 1985). Removal of these lipids renders the translocator inactive, but activity can be reconstituted by adding cardiolipin. It has also a pivotal role as a boundary hpid of various proteins such as NADH ubiquinone oxireductase (Hoch, 1992) or cytochrome c oxidase (Ushmorov et al, 1999 Vik et al, 1981). 

Rytdmaa, M., and Kinnunen, P.K.J., 1995, ReversibUity of the binding of cytochrome c to Uposomes. Implications for lipid-protein interactions./. B/oZ. Chem., 270 3197-3202 Salamon, Z., and ToUin, G., 1996, Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar Upid bUayer. II. Binding of cytochrome c to oxidase-containing cardiohpin /phosphatidylcholine membranes. Biophys. J., 71 858-867 Salamon, Z., and ToUin, G., 1997, Interaction ofhorse heart cytochrome c with Upid bilayer membranes effects on redox potentials. J. Bioenerg. Biomembr. 29 211-221 Scarlett, J.L., and Murphy, M.P., 1997, Release of apoptogenic proteins from the... 

Doxombicin binds readily to ceU membranes, changing their structure and function. The targets of doxombicin binding are compounds with a negative charge, of which the most extensively studied is the phospholipid cardiolipin (Pollakis et ah, 1983). Cardiolipin occurs in high concentrations in the inner mitochondrial membrane, where it is required for full activity of cytochrome c oxidase. In a recent study (Das and Mazumdar, 2000), the interaction between cytochrome c oxidase and cardiohpin in the presence of doxombicin was analysed, and the results of pico-second time-resolved fluorescence depolarization showed that the cardiohpin layer was depleted due to complexation with the dmg. 

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