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Mixed-function oxidase protein

Gozukara EM, Belvedere G, Robinson RC, Deutsch J, Coon MJ, Guengerich FP, Gelboin HV. The effect of epoxide hydratase on benzo[a]pyrene diol epoxide hydrolysis and binding to DNA and mixed-function oxidase proteins. Mol Pharmacol 1981 19 153-161. [Pg.32]

Seasonal Study of Mixed Function Oxidases.— A seasonal study of hepatic microsomal mfo components has been conducted in female R and S fish (submitted for publication). Components studied were cytochromes P-450 and 5, NADPH-cytochrome c reductase, NADPH-dichlorophenolindophenol reductase, NADH-cytochrome c reductase and NADH-cytochrome 5 reductase. All were monitored at 30°C by standard spectrophotometric methods following optimization procedures (8, 9 > 10, n, J 2). Microsomal and total hepatic protein (137 and liver weight to body weight ratios were also monitored. [Pg.151]

The plasma protein binding of tacrolimus is approximately 99%. Tacrolimus is bound mainly to albumin and alpha-1-acid glycoprotein and has a high level of association with erythrocytes. It is extensively metabolized by the mixed-function oxidase system, primarily the cytochrome P450 system (CYP3A). The disposition of tacrolimus from whole blood was biphasic with a terminal elimination half-life of 11.7 hours in liver transplant patients. [Pg.1936]

Adrenodoxin. Adrenodoxin is the only iron-sulfur protein which has been isolated from mammals. This protein from mitochondria of bovine adrenal cortex was purified almost simultaneously by Kimura and Suzuki (32) and Omura et al. (33). It has a molecular weight of 12,638 (34) and the oxidized form of the protein shows maximal absorbances at 415 and 453 nm. Adrenodoxin acts as an electron carrier protein in the enzyme system required for steroid hydroxylation in adrenal mitochondria. In this system, electron transfer is involved with three proteins cytochrome P. gQ, adrenodoxin and a flavoprotein. Reduced NADP gives an electron to Tne flavoprotein which passes the electron to adrenodoxin. Finally, reduced adrenodoxin transfers the electron to cytochrome Pas shown in Fig. 3. The mechanism of cytochrome P cq interaction with steroid, oxygen and adrenodoxin in mixed-function oxidase of adrenal cortex mitochondria has been reviewed by Estabrook et al. (35). [Pg.113]

Putidaredoxin. Cushman et al. (36) isolated a low molecular iron-sulfur protein from camphor-grown Pseudomonas putida. This protein, putidaredoxin, is similar to the plant type ferredoxins with two irons attached to two acid-labile sulfur atoms (37). It has a molecular weight of 12,000 and shows absorption maxima at 327, 425 and 455 nm. Putidaredoxin functions as an electron transfer component of a methylene hydroxylase system involved in camphor hydroxylation by P. putida. This enzyme system consists of putidaredoxin, flavoprotein and cytochrome P.cQ (38). The electron transport from flavoprotein to cytochrome P.cq is Smilar to that of the mammalian mixed-function oxidase, but requires NADH as a primary electron donor as shown in Fig. 4. In this bacterial mixed-function oxidase system, reduced putidaredoxin donates an electron to substrate-bound cytochrome P. g, and the reduced cytochrome P. g binds to molecular oxygen. One oxygen atom is then used for substrate oxidation, and the other one is reduced to water (39, 40). [Pg.113]

Megaredoxin. Another example of a bacterial mixed-function oxidase was found in the steroid 15 6-hydroxylase system of Bacillus megaterium (41). This enzyme system consists of three proteins FMN-containing flavoprotein (megaredoxin reductase), iron-sulfur protein... [Pg.113]

It has been well recognized that the mixed-function oxidase system of Bacillus megaterium is involved in steroid hydroxylation (, as already described above. This enzyme system is composed of a NADPH-specific FMN flavoprotein (megaredoxin reductase), an iron-sulfur protein (megaredoxin) and cytochrome P cn. The megaredoxin protein plays an important role as an intermediate component of electron transfer from reduced flavoprotein to cytochrome P en. [Pg.124]

FIGURE 21-47 Side-chain cleavage in the synthesis of steroid hormones. Cytochrome P-450 acts as electron carrier in this mixed-function oxidase system that oxidizes adjacent carbons. The process also requires the electron-transferring proteins adrenodoxin and adrenodoxin reductase. This system for cleaving side chains is found in mitochondria of the adrenal cortex, where active steroid production occurs. Pregnenolone is the precursor of all other steroid hormones (see Fig. 21-46). [Pg.828]

We observed a protective effect of increased dietary protein on DMBA-induced breast tumor incidence when the diets varying in protein were fed prior to carcinogen administration. We have investigated the hypothesis that dietary protein may influence carcinogenesis via effects on the mixed-function oxidase (MFO) enzyme systems involved in carcinogen metabolism. [Pg.318]

Figure 5. Dietary protein and hepatic mixed function oxidase activity (cytochrome c-reductase, cytochrome P-450, aryl hydrocarbon hydroxylase). (Reproduced with permission from Ref. 71. Copyright 1983, American Dairy Science Association.)... Figure 5. Dietary protein and hepatic mixed function oxidase activity (cytochrome c-reductase, cytochrome P-450, aryl hydrocarbon hydroxylase). (Reproduced with permission from Ref. 71. Copyright 1983, American Dairy Science Association.)...
For most drugs, oxidative biotransformation is performed primarily by the mixed-function oxidase enzyme system, which is present predominantly in the smooth endoplasmic reticulum of the liver. This system comprises (1) the enzyme NADPH cytochrome P450 reductase (2) cytochrome P450, a family of heme-containing proteins that catalyze a variety of oxidative and reductive reactions and (3) a phospholipid bilayer that facilitates interaction between the two proteins. Important exceptions to this rule are ethyl alcohol and caffeine, which are oxidatively metabolized by enzymes primarily present in the soluble, cytosolic fraction of the liver. [Pg.46]

The mixed-function oxidase system is composed of which of the following a a superfamily of heme-containing proteins... [Pg.60]


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See also in sourсe #XX -- [ Pg.322 ]




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Functional protein-functionalized

Functionality protein

Mixing functions

Oxidases mixed-function

Proteins functioning

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