scholarly journals Properties of a cytochrome c-enriched light particulate fraction isolated from the photosynthetic bacterium Rhodopseudomonas spheroides

1978 ◽  
Vol 174 (1) ◽  
pp. 267-275 ◽  
Author(s):  
J Barrett ◽  
C N Hunter ◽  
O T G Jones
Keyword(s):  
Cytochrome C ◽  
Sodium Dodecyl ◽  
Photosynthetic Bacterium ◽  
Particulate Fraction ◽  
Cytochrome C Reductase ◽  
Cytochrome C2 ◽  
Succinate Cytochrome C Reductase ◽  
Bulk Membrane ◽  
Nadh Cytochrome ◽  
Rhodopseudomonas Spheroides

Differential centrifugation of suspensions of French-press-disrupted Rhodopseudomonas spheroides yielded a light particulate fraction that was different in many properties from the bulk membrane fraction. It was enriched in cytochrome c and had a low cytochrome b content. When prepared from photosynthetically grown cells this fraction had a very low specific bacteriochlorophyll content. The cytochrome c of the light particles differed in absorption maxima at 77K from cytochrome c2 attached to membranes; there was pronounced splitting of the alpha-band, as is found in cytochrome c2 free in solution. Potentiometric titration at A552–A540 showed the presence of two components that fitted an n = 1 titration; one component had a midpoint redox potential of +345mV, like cytochrome c2 in solution, and the second had E0′ at pH 7.0 of +110 mV, and they were present in a ratio of approx. 2:3. Difference spectroscopy at 77K showed that the spectra of the two components were very similar. More of a CO-binding component was present in particles from photosynthetically grown cells. Light membranes purified by centrifugation on gradients of 5–60% (w/w) sucrose retained the two c cytochromes; they contained no detectable succinate-cytochrome c reductase or bacteriochlorophyll and very little ubiquinone, but they contained NADH-cytochrome c reductase and some phosphate. Electrophoresis on sodium dodecyl sulphate/polyacrylamide gels showed that the light membranes of aerobically and photosynthetically grown cells were very similar and differed greatly from other membrane fractions of R. spheroides.

VALUE OF CONTROL THEORY IN THE STUDY OF CELLULAR METABOLISM — BIOMEDICAL IMPLICATIONS

1995 ◽  
Vol 03 (01) ◽  
pp. 165-175 ◽  
Author(s):  
MONIQUE MALGAT ◽  
THIERRY LETELLIER ◽  
SOPHIE L. JOUAVILLE ◽  
JEAN-PIERRE MAZAT
Keyword(s):  
Cytochrome C ◽  
Control Theory ◽  
Metabolic Networks ◽  
Threshold Effect ◽  
Cytochrome C Reductase ◽  
Succinate Cytochrome C Reductase ◽  
Nadh Cytochrome ◽  
Metabolic Control Theory ◽  
Control Coefficients

We use some examples to show that Metabolic Control Theory (MTC) not only allows the determination of the controlling steps of a metabolic network with the so-called control coefficients, but also leads to better understanding of the functioning of metabolic networks. The examples are taken partly from our own work on mitochondrial myopathies, partly from the literature: — the threshold effect observed in mitochondria diseases; — the problem of the diagnosis of complex I, II or III defects by measuring the NADH-cytochrome-c-reductase or the succinate-cytochrome-c-reductase activities with illustration by some cases. The possibility of a sum of control coefficients greater than one is also considered.

Subcellular fractionation of the porcine corpus luteum: sequestration of progesterone in a unique particulate fraction

1988 ◽  
Vol 117 (3) ◽  
pp. 341-354 ◽  
Author(s):  
T. A. Bramley ◽  
G. S. Menzies
Keyword(s):  
Cytochrome C ◽  
Cell Surface ◽  
Corpus Luteum ◽  
Reductase Activity ◽  
Buoyant Density ◽  
Particulate Fraction ◽  
Luteal Cell ◽  
Cytochrome C Reductase ◽  
Intracellular Organelles ◽  
Nadh Cytochrome

ABSTRACT Homogenates of porcine corpus luteum were subjected to fractionation by differential-rate centrifugation or sucrose density gradient fractionation, with or without pretreatment with digitonin. Fractions of each gradient were assayed for a number of markers characteristic of the major intracellular organelles and cell-surface membranes, and for progesterone content. The majority of the progesterone content of homogenates of porcine corpus luteum was associated with a low-density particulate fraction which equilibrated at a buoyant density of 1·07–1·09 g/cm3. Pretreatment with digitonin increased the buoyant density of the progesterone-enriched fraction markedly (to 1·13–1·15 g/cm3) without causing release of steroid. The density distributions of progesterone content in control and digitonin-treated luteal gradient fractions were quite distinct from those of the major intracellular organelles and luteal cell-surface membranes. However, NADH–cytochrome C reductase activity (but not other endoplasmic reticulum markers) was also enriched in this fraction. The results suggest that most of the progesterone of the porcine corpus luteum is associated with a unique particulate fraction which is enriched in digitonin-reactive lipids and NADH–cytochrome C reductase activity. J. Endocr. (1988) 117, 341–354

Endoplasmic reticulum membrane isolated from small-intestinal epithelial cells: enzyme and protein components

1981 ◽  
Vol 52 (1) ◽  
pp. 215-222
Author(s):  
M. Fujita ◽  
H. Ohta ◽  
T. Uezato
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Cytochrome C ◽  
Endoplasmic Reticulum Membrane ◽  
Dependent Manner ◽  
Cytochrome C Reductase ◽  
Basolateral Membranes ◽  
Nadh Cytochrome ◽  
Protein Components ◽  
A Minor

Endoplasmic reticulum membrane-rich fraction was obtained by subfractionation of the light microsomes from mouse jejunal mucosal epithelial cells. It was marked by high glucose-6-phosphatase, NADPH-cytochrome c reductase, and NADH-cytochrome c reductase activities and low Na+,K+-ATPase activity. The enrichment of Na+,K+-ATPase was 180-fold higher in the basolateral membranes than in the endoplasmic reticulum membrane-rich fraction relative to glucose-6-phosphatase. The protein peak that was phosphorylated in a Na-dependent manner was prominent in the basolateral membranes while it was a minor peak in the endoplasmic reticulum membrane-rich fraction. Under the electron microscope the fraction was seen to be composed of homogeneous small vesicles with thin smooth membranes.

Ferrocyanide-activated NADH cytochrome c reductase from barley

1980 ◽  
Vol 18 (4) ◽  
pp. 389-393 ◽  
Author(s):  
Ian S. Small ◽  
John L. Wray
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Reductase ◽  
Nadh Cytochrome
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