Cytochrome labeled, isolation

Halestrap initially concluded that the increases in mitochondrial pyruvate transport and carboxylation were due to an increase in A pH secondary to stimulation of the electron transport chain in the cytochrome fee, region [255]. The conclusion was based largely on spectral measurements of the redox state of these cytochromes in the control and stimulated states. The spectral measurements were later found to be artifactual due to low amplitude Ca swelling of the mitochondria. Halestrap then suggested that the stable changes in the mitochondria might reside in the lipid components of the membrane due to phospholipase A 2 activity [261,262], but he has been unable to confirm this with lysophospholipid measurements [263]. On the other hand, using an EPR spin label probe of the lipid environment of the isolated mitochondria, Hoek has found differences between control and treated mitochondria [264]. 

C, 02]acetate exhibited that " 0-isotope-induced shifts were observed at C-16 and C-18 but not at C-1, C-2 and C-8 [43]. When P. betae was treated with cytochrome P450 inhibitor, ancymidol (1 mM), a less oxidized precursor named probetaenone I (57) was obtained [43]. Tbe structure and stereochemistry were confirmed by extensive NMR analysis and chiral synthesis via the similar route to that of betaenone C (50) [44]. Feeding experiments of C-labeled probetaenone I (57) demonstrated that the intermediate (57) was converted to betaenone B (49) [45]. Isolation of probetaenone I (57)... 

Halogenated Hydrocarbons - The destruction of cytochrome P-450 by CCl, first attributed to lipid peroxidation, has been shown to occur even under conditions where lipid peroxidation is not detectable.one possible explanation for this inactivation is that the trlchloromethyl radical or a related species obtained by reduction of the halocarbon reacts with the heme moiety or the apoprotein. The ill-defined radio-labeled porphyrins reported in Incubations of labeled CCI4 with hepatic microsomes would provide support for a heme alkylation mechanism were it not for the conflicting report that fluorescent N-alkylated porphyrins similar to those obtained with AIA are not isolated from CCl -incubated microsomes by procedures that result in isolation of the AIA adducts. ... 

Alizadeh S, Morals F, Barber ] et al. Isotopic labelling of the polypeptide subunits of the isolated photosystem II reaction-center complex of Chlamydomonas reihnhardtii suggests an ap heterodimeric structure for cytochrome b-550. J Photochem Photobiol 1999 48 148-153. 

Signification of results with isolated mitochondria. The site of incorporation of radioactive amino acids in vitro is almost exclusively insoluble membrane-bound protein (structural protein(s)) while soluble proteins, i.e. those readily lost from mitochondria are unlabelled. A comparable situation is observed with isolated chloroplasts. The comparison of the labelling of the mitochondrial substructures after careful fractionation shows that it is predominantly the inner membrane which is active in protein synthesis. It is concluded that soluble enzymes (cytochrome c, dehydrogenases are easily dissolved) and the outer mitochondrial membranes are synthesized outside of the mitochondria in vivo. 

We have isolated reaction centers from Rhodospirillum rubrum G- 9 cells labeled with the isotope 39-Fe. On LDS-polyacrylamide electrophoresis the preparation shows the typical three bands H, M and L and some minor contaminations (Figure 1). The specific staining technique for c-type cytochromes gave no positive reaction, indicating that there is no such cytochrome among the contaminations (datanot shown). 

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