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Biomedical subjects

M Teubner

Publications and source records attributed to M Teubner.

5 recordsLinked to original sources
PubMed1979

Electrostatic interactions at charged lipid membranes. Calcium binding.

A quantitative study of calcium-ion binding by the negatively-charged phospholipid methylphosphatidic acid is presented. Experimental results are compared with the predictions of the Gouy-Chapman theory, taking into account both the ions bound at the membrane surface and the ions held in the diffuse layer. This theory suffices to explain the titration of the calcium/lipid system, but fails to explain completely the behaviour of the ordered-fluid transition temperature, which shows a splitting that according to electrostatic theory alone should not occur. The dependence of the calcium-lipid binding constant. upon 1: 1 electrolyte concentration is correctly predicted by the theory; the latter however gives equations which can only be solved numerically. A simple, approximate equation is therefore given (in the text, eq. 34) for the prediction of the degree of calcium binding to a negatively-charged lipid membrane.

Journal Article↗
PubMed1976

Electrostatic interactions at charged lipid membranes. I. Effects of pH and univalent cations on membrane structure.

Electrostatic interactions at charged lipid membranes make a significant contribution to the free energy of the system, and can be varied within a wide range by alteration either of the membrane's surface charge density or of the concentration of electrolytes in the surrounding medium. Changes in the charged membrane's structure, such as the ordered in equilibrium fluid phase transition, can thus be induced at constant temperature by variations in pH and salt concentration. An adequate quantitative description of these phenomena is obtained from the Gouy--Chapman theory. The good agreement between theory and experiment confirms that the expression derived for the electrostatic free energy especially in respect of its positive sign is correct. The classical expression derived for the electrostatic free energy, especially in respect of its positive sign, is correct. The classical expression for the "free energy of the double layer" derived by Verwey and Overbeek, which has a negative sign, is not applicable to lipid membranes with ionizable polar groups.

Cations, Monovalent↗