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G Swoboda

Publications and source records attributed to G Swoboda.

14 recordsLinked to original sources
PubMed1988

Inactivation of detergent-solubilized sarcoplasmic reticulum ATPase.

Inactivation of sarcoplasmic ATPase in the solubilized state was studied in the absence and presence of Ca2+, Mg2+ and glycerol. The effects of the detergents octa(ethyleneglycol) mono-n-dodecyl ether (C12E8), 1-O-tetradecylpropanediol-(1,3)-3-phosphorylcholine and myristoylglycerophosphocholine were compared. All three detergents caused a rapid decline of the dinitrophenyl phosphatase activity of the unprotected enzyme. The stabilizing effect of Ca2+ ions was kinetically analysed. It was found that the stability of the solubilized enzyme depends on the Ca2+ concentration in a manner which is best explained by assuming rapid inactivation of Ca2+-free enzyme accompanied by slow inactivation of a calcium-enzyme complex (E1Ca). The apparent affinity constants obtained are in the order of 10(6)M-1, suggesting that high-affinity Ca2+ binding must be involved. No indications of a contribution were found, either of low-affinity Ca2+-binding sites of the conformational state E2 or of the high-affinity calcium complex E1Ca2. If Ca2+ was replaced by Mg2+, which exerts a weaker protection, the apparent affinity constants for Mg2+ are in the range of 1 mM-1. The stoichiometry of the effect of Mg2+ depends on the detergent.

4-Nitrophenylphosphatase↗
PubMed1985

[Extreme kidney displacement caused by an adrenal pseudocyst].

Renal displacement is very infrequently associated with a space occupying adrenal disease and sometimes imposes major diagnostic problems. The diagnosis of monstrous, retroperitoneal cysts is of particular difficulty. In a 51-year-old female patient the diagnosis and the association of a cystic formation to the adrenal gland could only be made at surgery, despite the steadily increasing renal displacement. The etiology of adrenal cysts, the diagnostic procedures and the possible concurrence of hypertension are discussed.

Adrenal Gland Diseases↗
PubMed1979

Effects of phospholipase A2 and albumin on the calcium-dependent ATPase and the lipid composition of sarcoplasmic membranes.

1. The calcium-dependent ATPase activity of phospholipase-A2-digested sarcoplasmic vesicles decreases concomitantly with the contents of residual lysophospholipids and fatty acids when increasing albumin concentrations are applied. 2. Delipidated albumin preferentially removes unsaturated fatty acids and lysophosphatidylcholine. A complete removal of the phospholipids by albumin does not occur. 3. The membrane-bound lysophospholipids were analysed with respect to type of phospholipid, plasmalogen content and fatty acid chains by means of thin-layer chromatography and gas chromatography. 4. While the fatty acid composition of the lysophospholipids is independent of the degree of delipidation, the composition of the residual free fatty acids is found to change with the albumin concentration. 5. Reactivation of the Ca2+-ATPase by oleate leads to reasonable activities at room temperature as long as a minimum of about 30 lysophospholipid molec-les per ATPase is left. The course of the residual Ca2+-ATPase activity with the degree of delipidation is related to the presence of unsaturated fatty acids. 6. No specific role of either sphingomyelin or the plasmalogens has been found.

Animals↗
PubMed1979

[Comparative studies of radioisotope uroflowmetry (author's transl)].

Radioisotope uroflowmetry allows continuous recording of urinary stream with determination of maximum and mean urine flow rate, duration of voiding and residual urine without urethral catheterisation. By the aid of twenty simulated tests and nine examinated patients the precision of this method was investigated by comparing our results with the findings of simultaneously recorded mictiographic measurement. The flow curves and the maximum flow rate show a high correlation.

Humans↗
PubMed1978

[Rare arterial variations during upper abdominal and pancreatic angiography (author's transl)].

Selected cases showing rare variations of the arteries of the upper abdomen indicate how difficult the exact identification of individual vessels can be. In the presence of such variations, which usually involve several vessels, it is essential to find and demonstrate all vessels in the upper abdomen. Vessels which are not seen easily must also be specially searched for. In the presence of anomalous vessels, angiography may prevent the surgeon from ligating the incorrect arteries during operation on the pancreas, the liver, stomach, spleen or colon.

Abdomen↗
PubMedDate not supplied

Bile salt delipidation, residual phospholipids and reactivation of the Ca2+-ATPase from sarcoplasmic reticulum.

1. Delipidation of the Ca2+-ATPase of sarcoplasmic reticulum membranes by gel chromatography employing ionic detergents (cholate, deoxycholate and mixtures of both) in the presence of glycerol has been studied with respect to residual phospholipids and ATPase activities. 2. The extent of delipidation depends on the detergent chosen and on the ionic strength of the elution buffer. Increasing ionic strength favours a more effective removal of phospholipids, down to about 1 phospholipid molecule per ATPase molecule. 3. The residual ATPase activities of the delipidated preparations are negligibly low. Extensive restoration of the Ca2+-dependent ATPase activity has been achieved by oleic acid, a lysolecithin (myristoylglycerophosphocholine) and a lecithin (dimyristoylglycerophosphocholine). The percentage of reactivation by oleate depends linearly on the amount of residual phospholipids and on the detergent employed. 4. After gel filtration through an Ultrogel or Sepharose column containing 1% cholate in the elution buffer the delipidated ATPase is eluted as a reactivatable high molecular aggregate, whereas 1% deoxycholate favours the formation of completely lipid-free monomeric units which cannot be reactivated, however. A high molecular aggregate is also formed in deoxycholate, the ratio of monomer to polymer depending on the solubilizing and elution conditions. 5. The residual lipids are always composed of a mixture of all different lipid classes present in the native sarcoplasmic vesicles, even at high degrees of delipidation. Specific changes with varying extent of delipidation were not detected.

Animals↗
PubMedDate not supplied

Transient activation of the Ca2+-ATPase from sarcoplasmic reticulum during thiol modification by 5,5'-dithiobis(2-nitrobenzoate).

In the reaction of sarcoplasmic reticulum membranes with excess 5,5'-dithiobis(2-nitrobenzoate) (DTNB) some new features were observed: The Ca2+-dependent ATPase activities of increasingly modified preparations were considerably enhanced during the initial stage of thiol blockage. A maximum (130-160% of the control activity) was reached when about 1.5-2 mol thiol groups per 10(5) g vesicular protein had reacted, in the absence of ATP and detergent. At higher extents of modification inactivation occurred. Purified ATPase behaved principally similar to native sarcoplasmic vesicles. In the presence of Mg2+ and ATP the activity maximum (up to 180% of control) was broadened and shifted towards a higher degree of thiol blockage. Concomitantly the modification and inactivation rates were considerably reduced. Glycerol (10-30%, v/v) slightly enhanced the ATPase activity maximum and reduced the rate of inactivation essentially only by decreasing the DTNB modification rate. In the presence of sufficient myristoylglycerophosphocholine for solubilization no activation was observed. The steady state level of phosphoprotein from ATP was raised to about 150% of the control level 10 s after addition of DTNB (about 1/2 thiol blocked), followed by a linear decrease with the number of thiols labeled, while the Ca2+-dependent ATPase activity of preparations modified under equivalent conditions (10(-4) M Ca2+ and 2 X 10(-3) M Mg2+ present) showed a broader maximum corresponding to 1.5 thiols blocked.

Adenosine Triphosphate↗
PubMedDate not supplied

Reaction of fluorescein isothiocyanate with thiol and amino groups of sarcoplasmic ATPase.

Several model compounds containing thiol and/or amino groups (mercaptoethanol, glutathione, cysteine, ethanolamine, glycine) were studied with respect to their reactivity towards fluorescein isothiocyanate (followed spectrophotometrically at 504 and 412 nm), stability of product and long-wave absorption maximum of the fluorescein residue attached. Thiol groups reacted by far more readily than amino groups. A specific effect was observed with cysteine, indicating an intramolecular transfer of the fluorescein residue from SH to NH2. With sarcoplasmic vesicles both types of reactions were observed. The ratio of products, which can be distinguished by their different stabilities and absorption spectra, depended on the absence or presence of detergents. While with native vesicles the NH2 reaction predominated, with vesicles solubilized with sodium dodecylsulfate, octaethyleneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine the SH reaction became prevailing. Already 0.35 mg sodium dodecylsulfate per mg protein were sufficient to give rise to dithiourethane formation exclusively. Excess fluorescein isothiocyanate reacted with several thiol groups of dodecylsulfate-solubilized vesicles. In the presence of ATP binding of fluorescein isothiocyanate to native vesicles was significantly reduced. Total blockage of the vesicular SH groups with N-ethyl-maleimide led to preparations that reacted with fluorescein isothiocyanate much more slowly, compared to native vesicles. Octaethyleneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine in the assay accelerated the thioureide formation from N-ethylmaleimide modified vesicles, whereas sodium dodecylsulfate prevented it almost completely. Our results support the suggestion that one or several thiol groups in vicinity of the highly reactive lysyl residue might play a role in the fast specific reaction, which is only observed with intact native vesicles.

Adenosine Triphosphatases↗