Differing Populations of Mitochondria Isolated from the Skeletal Muscle of Normal and Dystrophic Hamsters

1974 ◽  
Vol 52 (11) ◽  
pp. 1024-1032 ◽  
Author(s):  
B. J. Mezon ◽  
K. Wrogemann ◽  
M. C. Blanchaer
Keyword(s):  
Skeletal Muscle ◽  
Oxidative Phosphorylation ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Ruthenium Red ◽  
Dystrophic Muscle ◽  
Sucrose Density Gradient Centrifugation ◽  
Muscle Mitochondria ◽  
High Calcium

Polarographic studies of a magnesium-responsive, calcium-associated defect of oxidative phosphorylation in dystrophic hamster skeletal muscle suggested that all dystrophic mitochondria are defective. This is at variance with the typical histological picture of dystrophic muscle, which shows, besides defective muscle fibers, many apparently normal cells, with presumably normal mitochondria. This discrepancy was resolved by linear sucrose density-gradient centrifugation (39–51%, w/v), which can separate normal mitochondria from calcium-loaded organelles. Upon density-gradient centrifugation of control and dystrophic muscle mitochondria, both preparations were found to yield suspended bands of similar density. However, the dystrophic preparations also produced a pellet at the bottom (most dense region) of the tube with calcium levels 10–40 times higher than those in the suspended bands. The data show the existence in dystrophic muscle of a distinct population of mitochondria with very high calcium levels that is absent from normal preparations. During the course of oxidative phosphorylation measurements, loss of calcium from these particular organelles and its uptake by others appear to render all the mitochondria defective. This exchange can be prevented by ruthenium red. Density-gradient centrifugation allows the identification of dystrophic muscle mitochondria in early and/or mild disease stages in which polarographic testing of mitochondria isolated by conventional centrifugation fails to detect an abnormality.

The Combining Ability of Glycoproteins IIb, IIIa and Ca2+ in EDTA-Treated Nonaggregable Platelets

1983 ◽  
Vol 50 (04) ◽  
pp. 848-851 ◽  
Author(s):  
Marjorie B Zucker ◽  
David Varon ◽  
Nicholas C Masiello ◽  
Simon Karpatkin
Keyword(s):  
Density Gradient ◽  
Combining Ability ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Electrophoretic Pattern ◽  
Sucrose Density Gradient ◽  
Irreversible Loss ◽  
Sucrose Density Gradient Centrifugation ◽  
Crossed Immunoelectrophoresis ◽  
Triton X

SummaryPlatelets deprived of calcium and incubated at 37° C for 10 min lose their ability to bind fibrinogen or aggregate with ADP when adequate concentrations of calcium are restored. Since the calcium complex of glycoproteins (GP) IIb and IIIa is the presumed receptor for fibrinogen, it seemed appropriate to examine the behavior of these glycoproteins in incubated non-aggregable platelets. No differences were noted in the electrophoretic pattern of nonaggregable EDTA-treated and aggregable control CaEDTA-treated platelets when SDS gels of Triton X- 114 fractions were stained with silver. GP IIb and IIIa were extracted from either nonaggregable EDTA-treated platelets or aggregable control platelets with calcium-Tris-Triton buffer and subjected to sucrose density gradient centrifugation or crossed immunoelectrophoresis. With both types of platelets, these glycoproteins formed a complex in the presence of calcium. If the glycoproteins were extracted with EDTA-Tris-Triton buffer, or if Triton-solubilized platelet membranes were incubated with EGTA at 37° C for 30 min, GP IIb and IIIa were unable to form a complex in the presence of calcium. We conclude that inability of extracted GP IIb and IIIa to combine in the presence of calcium is not responsible for the irreversible loss of aggregability that occurs when whole platelets are incubated with EDTA at 37° C.

scholarly journals Purification of Torpedo californica post-synaptic membranes and fractionation of their constituent proteins

1980 ◽  
Vol 185 (3) ◽  
pp. 667-677 ◽  
Author(s):  
J Elliott ◽  
S G Blanchard ◽  
W Wu ◽  
J Miller ◽  
C D Strader ◽  
...  
Keyword(s):  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Selective Extraction ◽  
Synaptic Membranes ◽  
Detergent Solution ◽  
Major Step ◽  
Sucrose Density Gradient Centrifugation ◽  
Torpedo Californica

A rapid methof for preparation of membrane fractions highly enriched in nicotinic acetylcholine receptor from Torpedo californica electroplax is described. The major step in this purification involves sucrose-density-gradient centrifugation in a reorienting rotor. Further purification of these membranes can be achieved by selective extraction of proteins by use of alkaline pH or by treatment with solutions of lithium di-idosalicylate. The alkali-treated membranes retain functional characteristics of the untreated membranes and in addition contain essentially only the four polypeptides (mol.wts. 40000, 50000, 60000 and 65000) characteristic of the receptor purified by affinity chromatography. Dissolution of the purified membranes or of the alkali-treated purified membranes in sodium cholate solution followed by sucrose-density-gradient centrifugation in the same detergent solution yields solubilized receptor preparations comparable with the most highly purified protein obtained by affinity-chromatographic procedures.

scholarly journals Molecular size of the 5-HT3 receptor solubilized from NCB 20 cells

1990 ◽  
Vol 269 (3) ◽  
pp. 623-628 ◽  
Author(s):  
R M McKernan ◽  
C S Biggs ◽  
N Gillard ◽  
K Quirk ◽  
C I Ragan
Keyword(s):  
Physical Properties ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Receptor Site ◽  
Molecular Size ◽  
Sucrose Density Gradient ◽  
Partial Specific Volume ◽  
Sucrose Density Gradient Centrifugation ◽  
Ics 205 930

The 5-HT3 hydroxytryptamine receptor from NCB 20 cells was solubilized and the molecular and hydrodynamic properties of the receptor were investigated. The receptor was identified by binding of the radioligand 3-NN′-[3H]dimethyl-8-azabicyclo[3.2.1]octanyl indol-3-yl carboxylate ester [(3H]Q ICS 205-930) to NCB 20 membranes (Bmax = 1.19 +/- 0.31 pmol/mg of protein; Kd = 0.43 +/- 0.076 nM) and was optimally solubilized with 0.5% deoxycholate. [3H]Q ICS 205-930 labelled one population of sites in solution (Bmax = 1.11 +/- 0.4 pmol/mg of protein; Kd = 0.48 +/- 0.06 nM; n = 4). The characteristics of [3H]Q ICS 205-930 binding were essentially unchanged by solubilization, and competition for [3H]Q ICS 205-930 binding by a series of 5-HT3 agonists and antagonists was consistent with binding to a 5-HT3 receptor site and was similar to that observed for 5-HT3 receptors solubilized from rat brain [McKernan, Quirk, Jackson & Ragan (1990) J. Neurochem. 54, 924-930]. Some physical properties of the solubilized receptor were investigated. The molecular size (Stokes radius) of the [3H]Q ICS 205-930-binding site was measured by gel-exclusion chromatography in a buffer containing 0.2% Lubrol and 0.5 M-NaCl and was determined as 4.81 +/- 0.15 nm (mean +/- S.E.M.; n = 6). Sucrose-density-gradient centrifugation was also performed under the same detergent and salt conditions to determine the partial specific volume (v) of the detergent-receptor site complex. This was found to be 0.794 ml.g-1. Sucrose-density-gradient centrifugation was carried out in both 1H2O and 2H2O to allow correction for detergent binding to the receptor. The Mr of the 5-HT3 receptor under these conditions was calculated as 249,000 +/- 18,000 (n = 3). The size and physical properties of the 5-HT3 receptor are similar to those observed for members of the family of ligand-gated ion channels.

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