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Cytochrome reaction mechanism

Mayer, B., Heinzel, B.. Klatt, P., John M., Schmidt, K., and Bohme, E. (1992). Nitric oxide synthase-catalyzed activation of oxygen and reduction of cytochromes Reaction mechanisms and possible physiological implications. J. Cardiovasc. Pharmacol. 20, S54-S56. [Pg.260]

Chemical structure and reaction mechanisms of cytochrome c oxidase. R. Lemberg, Rev. Pure Appl. Chem., 1965,15,125-136 (132). [Pg.64]

Cytochrome P450 is considered the most versatile biocatalyst known. The actual reaction mechanism is complex and has been briefly described previously (Figure 11-6). It has been shown by the use of that one atom of oxygen enters R—OH and one atom enters water. This dual fate of the oxygen accounts for the former naming of monooxygenases as mixed-function oxidases. The reaction catalyzed by cytochrome P450 can also be represented as follows ... [Pg.627]

Cytochrome P450s catalyze reactions that introduce one atom of oxygen derived from molecular oxygen into the substrate, yielding a hydroxylated product. NADPH and NADPH-cytochrome P450 reductase are involved in the complex reaction mechanism. [Pg.632]

Gosh et al. reported LDA(SVWN) studies of oxo(porphyrinato)iron(IV) complexes.83 These compounds have been detected in various peroxidases and are believed to be involved in the reaction mechanisms of other heme enzymes, such as cytochromes P450. Very Good Fe-0 distance and values of unsealed stretching frequencies, which were in excellent agreement with CASSCF results, published elsewhere, were obtained. [Pg.95]

Orrenius, S. Reaction mechanisms of cytochrome P-1+50. Proceedings Sixth International Congress of Pharmacology, Helsinki, Finland (1975) 6, 39-52. [Pg.291]

These and other interesting results allow quantitative insight into the rate of breakdown of N-(hydroxymethyl) compounds (i.e., carbinolamines (hemi-aminals)), the reaction mechanisms of which we examined in Sect. 8.7.3 (see, in particular, Fig. 8.20) [80 - 82], These carbinolamines, we recall, are major metabolic intermediates in oxidative N-dealkylation reactions resulting from cytochrome P450 catalyzed hydroxylation of the C-atom adjacent to the... [Pg.704]

J. L. Boucher, M. Delaforge, D. Mansuy, Dehydration of Alkyl- and Arylaldoximes as a New Cytochrome P450-Catalyzed Reaction Mechanism and Stereochemical Characteristics , Biochemistry 1994, 33, 7811. 7818. [Pg.760]

Woggon, W.-D. Cytochrome P450 Significance, Reaction Mechanisms and Active Site Analogues. 184, 39-96 (1997). [Pg.184]

Willner I, Willner B (1991) Artificial Photosynthetic Model Systems Using Light-Induced Electron Transfer Reactions in Catalytic and Biocatalytic Assemblies. 159 153-218 Woggon W-D (1997) Cytochrome P450 Significance, Reaction Mechanisms and Active Site Analogues. 184 39 - 96... [Pg.321]

Cytochrome P450 Significance, Reaction Mechanisms and Active Site Analogues... [Pg.39]

Progress in decoding the mechanism of cytochrome P-450, which catalyzes epoxidation and hydroxylation of various hydrocarbons, has stimulated the search for comparatively simple and effective iron porphyrin systems [20-24], The reaction mechanism of monooxygenation can be illustrated by the following diagram ... [Pg.235]

The SOD activity is directly determined by following the decay of 05 or indirectly by competition between a monitoring molecule of 05 and SOD for 05. Cytochrome c, nitroblue tetrazolium, tetranitromethane and epinephrine have been used as the monitoring molecules of 05, and their reaction products are spectrophotometrically followed. Since the indirect methods do not require special apparatus, they have been widely used for the assay of SOD. For elucidation of the reaction mechanism, however, the direct methods using special apparatus are indispensable. [Pg.202]

Haem proteins that react with oxygen also utilise ferryl intermediates. Fig. 4 compares the (proposed) reaction mechanisms of cytochrome oxidase and cytochrome P-450 with those of peroxidases and catalases. As can be seen, several of the reaction intermediates have the same oxidation states (although the protonation steps and stage at which H2O is released may be different). However, in contrast to peroxidases, oxidases must react with molecular oxygen, and this requires a reaction cycle that includes Fe11. [Pg.78]

Fig. 4. A comparison of peroxidase, cytochrome c oxidase and cytochrome P-450 reaction mechanisms. Peroxidase mechanism adapted from that of Poulos[143], cytochrome P-450 mechanism adapted from that of Sligar [100], and cytochrome oxidase mechanism adapted from that of Babcock and Wikstrom[90]. RH, organic substrate for peroxidase and cytochrome P-450 (in the latter case the substrate is presumed to remain bound to the enzyme through most of the reaction cycle). Fig. 4. A comparison of peroxidase, cytochrome c oxidase and cytochrome P-450 reaction mechanisms. Peroxidase mechanism adapted from that of Poulos[143], cytochrome P-450 mechanism adapted from that of Sligar [100], and cytochrome oxidase mechanism adapted from that of Babcock and Wikstrom[90]. RH, organic substrate for peroxidase and cytochrome P-450 (in the latter case the substrate is presumed to remain bound to the enzyme through most of the reaction cycle).
The reaction mechanism of cytochrome bc complex is known as the proton motive Qcycle originally proposed by Peter Mitchell (Mitchell, 1976). This mechanism is the basis of his chemiosmotic theory for which he was awarded the Nobel prize in 1978. Since then, the enzyme has been characterized extensively using various techniques. Redox centers have been characterized spectroscopically (for review, see Trumpower and Gennis, 1994), electron transfer pathways have been determined using kinetic experiments with specific inhibitors (De Vries 1986 Zhu et al., 1984), and the positions of quinone binding sites and redox centers have been determined using biochemical and mutational analysis (for review, see Esposti et al, 1993 Brasseur et al, 1996). As a result of these efforts, the latest modified Qcycle has been widely accepted by researchers in the field (for reviews, see Crofts et al, 1983 Trumpower, 1990 Berry et al, 2000). [Pg.154]

In order to elucidate the reaction mechanism of cytochrome c oxidase, the complete structure of the enzyme must be determined. The first step in this process is the complete determination of its composition. X-ray crystallographic analysis at high resolution was required in addition to chemical analysis for crystalline enzyme preparation. [Pg.348]

Several enzymes with peroxidase-like action have also been used in immunoassays. Microperoxidases are catalytically active fragments obtained from cytochrome c by proteolytic action. They consist of the heme group covalently coupled to a short peptide alpha helix (26). The active site structure is similar to that of peroxidase Four of the six possible coordination bonds of the iron atom are occupied by bonding to the porphyrin while the fifth complexes with a histidine residue and the sixth is exposed to the environment and forms the catalytically active portion of the molecule. The reaction mechanism and spectrum of substrates is similar to HRP, although the specific activity is variable... [Pg.190]

The elucidation of the mode of interaction between cytochrome c peroxidase and cytochrome c is not only essential in our understanding of the reaction mechanism of this enzyme but also provides important clues for formulating a general mechanism of electron transfer in biological sys-... [Pg.356]


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See also in sourсe #XX -- [ Pg.95 , Pg.97 ]




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