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Biomedical subjects

E Weidekamm

Publications and source records attributed to E Weidekamm.

7 recordsLinked to original sources
PubMed1978

Phospholipid composition of human erythrocyte spectrin.

Human erythrocyte spectrin, which has been extracted at low ionic strength and precipitated at pH 5.1, contains 0.025 mumoles phospholipid/mg protein. The composition of the spectrin-phospholipids differs from that of the erythrocyte membrane. A remarkable similarity was found between the composition of the "available" phospholipids of the inner leaflet of the membrane bilayer and the spectrin-associated phospholipids. Rebinding studies with 125I-labeled spectrin show that the labeled spectrin binds preferentially to the cytoplasmic side of the membrane and that this binding is influenced by protein perturbations.

Erythrocyte Membrane↗
PubMed1977

Raman spectroscopic investigation of the interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes.

The interaction of gramicidin A with dipalmitoyl phosphatidylcholine liposomes is investigated by Laser-Raman spectroscopy. As revealed by the methylene C-H stretching mode the phase transition of the hydrocarbon chains near 40 degree C is eliminated in the presence of gramicidin A. Liposomes prepared from a mixture of lecithin and cholesterol seem to be unaffected by gramicidin A and show only the normal broadened phase transition.

Binding Sites↗
PubMed1976

Physical properties of muscle cell membranes during fusion. A fluorescence polarization study with the ionophore A23187.

1. The fluorescence polarization of A23187 is used to detect physical changes in myoblast membranes produced by Ca2+ concentrations which are able to trigger fusion. Temperature scans reveal a Ca2+-dependent fluidity increase in the microenvironment of the ionophore above 37 degree C. 2. Time-dependent polarization measurements show two different effects. The first one consists of a fast polarization increase which reaches its maximum after 5-10 min. This change could be explained by a Ca2+-induced phase separation of acidic and neutral phospholipids in the membrane. The second effect is a slow polarization decrease over 2-3 h subsequent to the fast increase. 3. The information derived from the fluorescence polarization is in accordance with the characteristics of the fusion of myoblast cells regarding the dependence on Ca2+ concentration, the inhibition by Mg2+ and lysolecithin as well as a typical temperature of 35-37 degree C where fusion rate changes abruptly.

Animals↗
PubMed1975

Extraction and localization of a (Ca2+ and Mg2+)-stimulated ATPase in human erythrocyte spectrin.

(1) A water soluble (Ca2+ plus Mg2+)-activated APTase has been extracted with 0.1 mM EDTA and 0.1 mM ATP from human erythrocyte membranes. (2) The specific activity of the extracted protein is increased 4- to 6-fold in comparison with untreated ghosts. (3) Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of [gamma-32P]ATP-labeled erythrocyte membranes shows that the (Ca2+ plus Mg2+)-activated ATPase is located in the "spectrin" region (Mr 220 000-240 000). The radioactivity of these high molecular peptide bands is decreased markedly after the extraction of the ATPase at low ionic strength.

Adenosine Triphosphatases↗