High impact information on CYTB

• Superoxide-producing cytochrome b. Enzymatic and electron paramagnetic resonance properties of cytochrome b558 purified from neutrophils [1].
• The reduced minus oxidized spectrum of these serotonin granule membranes shows a characteristic cytochrome b spectrum with absorbance maxima at 428, 530, and 561 nm [2].
• The calculated aerobic rate of cytochrome b reduction was equal to the measured rate of O2-. production in a variety of preparations and in the presence of a range of inhibitors [3].
• Three different additives, quinacrine, p-chloromercuribenzoate and cetyltrimethylammonium bromide, strongly inhibited O2.- generation; they also inhibited the reduction by NADPH of cytochrome b at the same low concentrations [4].
• The cytochrome b/FAD ratio was 1.13:1 in the crude solubilized extract and increased to 18.95:1 in the partially purified preparations [5].

Biological context of CYTB

• Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt-b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs [6].
• It was concluded that the appearance of the plateau between the two reduction phases of Q and b is caused by the rapid delivery of electrons to the high-potential components of the respiratory chain as envisaged in the Q cycle; the unexpected n value for cytochrome b suggests a concerted reduction by QH2 of two species of cytochromes b-562 [7].

Anatomical context of CYTB

• Intake of crystals involved preferential mobilisation of cytochrome b from the plasma membrane and the fusion of both specific and azurophil granules with the primary phagosome [8].

Associations of CYTB with chemical compounds

• The superoxide-generating oxidase of leucocytes. NADPH-dependent reduction of flavin and cytochrome b in solubilized preparations [4].
• The cytochrome b formed a complex with butyl isocyanide (close to 100% binding at 10mM); butyl isocyanide also inhibited the oxidase activity of stimulated whole neutrophils (22.5% inhibition at 10mM) [4].
• In an attempt to examine the cytochrome b translocation, porcine neutrophils were activated by treatment with surface-active agents such as myristate (MA) and phorbol myristate acetate (PMA), and then the postnuclear supernatants of both activated and unactivated cells were fractionated by Percoll density gradient centrifugation with a Zonal rotor [9].
• In presence of the inhibitors antimycin A or HQNO the reduction of cytochrome b became monophasic [10].
• 4. BAL treatment had a small effect on the midpoint potential of cytochrome b relative to that of the Q pool and had no effect on the n value [7].

Other interactions of CYTB

• These results are consistent with the postulated role of cytochrome b in O2.-formation by neutrophil NADPH oxidase, but raise doubts about the participation of flavoproteins in this enzyme activity [5].

References