In a cell-free apoptosis system, mitochondria spontaneously released cytochrome c, which activated DEVD-specific caspases, leading to fodrin cleavage and apoptotic nuclear morphology. Bcl-2 acted in situ on mitochondria to prevent the release of cytochrome c and thus caspase activation. During apoptosis in intact cells, cytochrome c translocation was similarly blocked by Bcl-2 but not by a casp...

Maximum concentrations of microsomal cytochrome P-450 are present in 3-4 day-old mung beans (Phaseolus aureus). On illumination of dark-grown seedlings, cytochrome P-450 and later cytochrome P-450 undergo a rapid decrease in concentration in vivo, with an apparent half-time of about 6 h. Conversely light-grown seedlings, transferred to darkness, show a slow accumulation of cytochrome P-450, dou...

We have defined conditions that permit quantitative and specific measurement of the metabolism of the major phenobarbital-inducible form of cytochrome P-450 protein in primary non-proliferating monolayer cultures of adult rat hepatocytes. Isolated antibodies specifically directed against phenobarbital cytochrome P-450 are used to immunoprecipitate the cytochrome from lysates of cultured hepatoc...

Release of mitochondrial cytochrome c into the cytosol is a critical step in apoptosis. We have reported that early release of cytochrome c in vivo occurs after permanent focal cerebral ischemia (FCI) and is mediated by the mitochondrial antioxidant manganese superoxide dismutase (SOD). However, the role of reactive oxygen species produced after ischemia-reperfusion in the mitochondrial apoptos...

Caffeine and 7,8-benzoflavone activate CYP3A2 in rat liver microsomes. Both activators appear to enhance enzyme activity by an increase in Vmax and to a lesser extent a decrease in Km. Additive effect studies demonstrated that the two activators oppose one another's effect. Electron transfer steps in the cytochrome P450 cycle are involved in the mechanism of cytochrome P450 activation, as indic...

The export of cytochrome c from mitochondria to the cytoplasm has been detected during apoptosis. Addition of cytochrome c to cytosolic extracts can activate the caspases, suggesting that this export could be an important intracellular signal for initiating the apoptotic programme. We have investigated the mechanism of caspase activation by cytochrome c. Mitochondrial cytochrome c normally shut...

The effects of digitonin and tocopherol on bovine heart reduced diphosphopyridine nucleotideand succinate-cytochrome c reductases and cytochrome c oxidase have been studied with the following results. 1. Low concentrations of digitonin stimulate succinateand DPNH-cytochrome c reductase and cytochrome c oxidase. Higher concentrations of digitonin completely inhibit cytochrome c reductases, while...

Using 1617 meaningful NOEs with 188 pseudocontact shifts, a family of 35 conformers of oxidized bovine microsomal cytochrome b5 mutant (E44/48/56A/D60A) has been obtained and is characterized by good resolution (rmsd to the mean structure are 0.047 +/- 0.007 nm and 0.095 +/- 0.008 nm for backbone and heavy atoms, respectively). The solution structure of the mutant, when compared with the X-ray ...

The involvement of cytochrome b561, an integral membrane protein, in electron transfer across chromaffin-vesicle membranes is confirmed by changes in its redox state observed as changes in the absorption spectrum occurring during electron transfer. In ascorbate-loaded chromaffin-vesicle ghosts, cytochrome b561 is nearly completely reduced and exhibits an absorption maximum at 561 nm. When ferri...