scholarly journals Evidence that coated vesicles isolated from brain are calcium-sequestering organelles resembling sarcoplasmic reticulum.

1977 ◽  
Vol 75 (1) ◽  
pp. 135-147 ◽  
Author(s):  
A L Blitz ◽  
R E Fine ◽  
P A Toselli
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Ions ◽  
Adenosine Triphosphatase ◽  
Sodium Dodecyl ◽  
Maximal Activity ◽  
Coated Vesicles ◽  
Potassium Oxalate ◽  
Triton X ◽  
Trapping Agent ◽  
The Brain

Coated vesicles from the brain have been purified to near morphological homogeneity by a modification of the method of Pearse. These vesicles resemble sarcoplasmic reticulum fragments isolated from skeletal muscle. They contain proteins with 100,000- and 55,000-dalton mol wt which co-migrate on polyacrylamide gels, in the presence of sodium dodecyl sulfate, with the two major proteins of the sarcoplasmic reticulum fragment. These vesicles contain adenosine triphosphatase (ATPase) activity which is stimulated by calcium ions in the presence of Triton X-100 (Rohm & Haas Co., Philadelphia, Pa.), displaying maximal activity at 8 x 10(-7) M Ca ++. They take up calcium ions from the medium, and this uptake is stimulated by ATP and by potassium oxalate, a calcium-trapping agent. The 100,000-dalton protein of the coated vesicles displays immunological reactivity with an antiserum directed against the 100,000-dalton, calcium-stimulated ATPase of the sarcoplasmic reticulum. As with the sarcoplasmic reticulum fragment, this protein becomes radiolabeled when coated vesicles are briefly incubated with gamma-labeled [32P]ATP. The possible functions of coated vesicles as calcium-sequestering organelles are discussed.

scholarly journals Studies on the in vivo sensitivity of spindle microtubules to calcium ions and evidence for a vesicular calcium-sequestering system.

1981 ◽  
Vol 88 (3) ◽  
pp. 604-617 ◽  
Author(s):  
D P Kiehart
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Vegetable Oil ◽  
Calcium Ions ◽  
Calcium Sensitivity ◽  
New Method ◽  
Distilled Water ◽  
Potassium Oxalate ◽  
Spindle Microtubules ◽  
Ca Oxalate

I microinjected calcium ions into echinoderm eggs during mitosis to determine the calcium sensitivity of microtubules (Mts) in vivo. Spindle birefringence (BR), a measure of the number of aligned Mts in the spindle, is locally, rapidly, and reversibly abolished by small volumes of microinjected CaCl2 (1 mM). Rapid return of BR is followed by anaphase, and subsequent divisions are normal. Similar doses of MgCl2, BaCl2, KCl, NaCl, pH buffers, distilled water, or vegetable oil have no effect on spindle BR, whereas large doses of such agents sometimes cause slow, uniform loss in BR over the course of a minute or more. Of the ions tested, only Sr++ causes effects comparable to Ca++. Ca-EGTA buffers, containing greater than micromolar free Ca++, abolishes BR in a manner similar to millimolar concentrations of injected CaCl2. Caffeine, a potent uncoupler of the Ca++-pump/ATPase of sarcoplasmic reticulum, causes a local, transient depression in spindle BR in the injected region. Finally, injection of potassium oxalate results in the formation of small, highly BR crystals, presumably CA-oxalate, in Triton-sensitive compartments in the cytoplasm. Taken together, these findings demonstrate that spindle Mts are sensitive to levels of free Ca++ in the physiological range, provide evidence for the existence of a strong cytoplasmic Ca++-sequestering system, and support the notion that Mt assembly and disassembly in local regions of the spindle may be orchestrated by local changes in the cytoplasmic free Ca++ concentration during mitosis. An appendix offers the design of a new chamber for immobilizing echinoderm eggs for injection, a new method for determining the volume of the injected solution, and a description of the microinjection technique, which was designed, but never fully described, by Hiramoto (Y. Hiramoto, Exp. Cell. Res., 1962, 27:416-426.).

scholarly journals The reactivity of the thiol groups of the adenosine triphosphatase of sarcoplasmic reticulum and their location on tryptic fragments of the molecule

1977 ◽  
Vol 167 (3) ◽  
pp. 739-748 ◽  
Author(s):  
David A. Thorley-Lawson ◽  
N. Michael Green
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Rate Constant ◽  
Adenosine Triphosphatase ◽  
Sodium Dodecyl ◽  
Thiol Group ◽  
Order Rate Constant ◽  
Reaction Rates ◽  
Cysteic Acid ◽  
Thiol Groups ◽  
Low Concentrations

The ATPase (adenosine triphosphatase) from sarcoplasmic reticulum contains 20 thiol groups/115000 daltons, measured by using either N-ethyl[14C]maleimide or 5,5′-dithiobis-(2-nitrobenzoate) in sodium dodecyl sulphate. After reduction there were 26 thiol groups, in good agreement with 26.5 residues of cysteic acid found by amino acid analysis. The difference between this and the 20 residues measured before reduction implies the presence of three disulphide residues. The same number of disulphide residues was found by direct measurement. Three to six fewer thiol groups were found in preparations made in the absence of dithiothreitol. The missing residues were accounted for as cysteic acid. The distribution of disulphide bonds and of exposed and buried thiol groups among the tryptic fragments of the molecule was measured after labelling with N-ethyl[14C]-maleimide. The disulphides were confined to fragment B (mol.wt. 55000), whereas several thiol groups were present on each of the fragments (A, B, A1 and A2). The kinetics of the reaction of the ATPase with 5,5′-dithiobis-(2-nitrobenzoate) showed that four or five of the thiol groups were unreactive in the absence of detergent and that 13 of the remainder reacted with a single first-order rate constant. In the presence of ATP and Ca2+ the reaction rate of all but two groups of this class was uniformly decreased. In the presence or absence of ATP and Ca2+ the rate constant for inactivation was close to the rate constant for this class, but was not identical with it. No selective protection of a specific active-site-thiol group was observed. Parallel experiments with sarcoplasmic reticulum gave similar results, except that the reaction rates were a little lower and there were two more buried groups. Solution of ATPase of sarcoplasmic reticulum in detergent greatly increased the reactivity of all thiol groups. The effects of low concentrations of deoxycholate were reversible. EGTA or low concentrations (0.02mm) of Ca2+ of Mg2+ had very little effect on the reactivity.

The Influence of Detergents on the Ca2+-and Mg2+-Dependent Adenosine Triphosphatase of the Sarcoplasmic Reticulum

1982 ◽  
Vol 37 (3-4) ◽  
pp. 299-307 ◽  
Author(s):  
Hans Lüdi ◽  
Bernhard Rauch ◽  
Wilhelm Hasselbach
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Ions ◽  
Inorganic Phosphate ◽  
Adenosine Triphosphatase ◽  
Tryptophan Fluorescence ◽  
The Other ◽  
Phosphorylated Protein ◽  
Intrinsic Tryptophan Fluorescence ◽  
Low Concentrations ◽  
Calcium Affinity

Abstract During the stepwise solubilization of sarcoplasmic reticulum vesicles with detergents, the following changes in the structural and enzymatic properties of the preparation are observed: 1. The viscosity of the vesicular suspension initially rises. This change is accompanied by the formation of elongated tubules. Subsequently the membranes are completely desintegrated, resulting in a considerable reduction of the viscosity. 2. A decrease in the activity of the Ca2+-dependent ATPase, which is restored after complete solubilization. 3. A decrease in the change of intrinsic tryptophan-fluorescence on removal of calcium ions, which is also restored after complete solubilization. 4. A decrease of the calcium affinity of the ATPase. 5. A decrease in the amount of phosphorylated protein formed by the incorporation of inorganic phosphate. On the other hand, the amount of phosphoprotein formed from ATP is not affected during solubilization. 6. The dependence of the initial rates of phosphoprotein formation from inorganic phosphate on either magnesium or inorganic phosphate at low concentrations of the respective ligand changes from an S-shape profile to a normal hyperbolic profile after solubilization.

Solubility and adsorption behaviors of chlorophenols in the presence of surfactant

1997 ◽  
Vol 35 (7) ◽  
pp. 123-130 ◽  
Author(s):  
J. C. Liu ◽  
P. S. Chang
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Critical Micelle Concentration ◽  
Sodium Dodecyl ◽  
Adsorption Behaviors ◽  
Brij 35 ◽  
Important Index ◽  
Dodecyl Sulfate ◽  
Triton X

The solubility of chlorophenols as affected by surfactant was investigated. Three kinds of surfactant, sodium dodecyl sulfate, Triton X-100, and Brij 35, were utilized. The solubilization of chlorophenols by surfactant follows the order of 2,4,6-trichlorophenol > 2,4-dichlorophenol > 2,6-dichlorophenol > 2-chlorophenol; and the critical micelle concentration is an important index. The adsorption reactions of 2,4-dichlorophenol and 2,4,6- trichlorophenol onto hydrous montmorillonite in the presence of surfactant were examined. The presence of surfactant decreased the adsorption of chlorophenols significantly. The roles of hydrophobicity of chlorophenols in solubilization and adsorption behaviors are discussed.

Different submicellar solubilization mechanisms revealed by 1H NMR and 2D diffusion ordered spectroscopy (DOSY)

2020 ◽  
Vol 22 (19) ◽  
pp. 11075-11085
Author(s):  
Mengjian Wu ◽  
Zhaoxia Wu ◽  
Shangwu Ding ◽  
Zhong Chen ◽  
Xiaohong Cui
Keyword(s):  
Nmr Spectroscopy ◽  
Sodium Dodecyl Sulfate ◽  
1H Nmr ◽  
Sodium Dodecyl ◽  
Butyl Methacrylate ◽  
H Nmr ◽  
Molecular Scale ◽  
Two Systems ◽  
Dodecyl Sulfate ◽  
Triton X

Different submicellar solubilization mechanisms of two systems, Triton X-100/tetradecane and sodium dodecyl sulfate (SDS)/butyl methacrylate, are revealed on the molecular scale by 1H NMR spectroscopy and 2D diffusion ordered spectroscopy (DOSY).

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