β Scribed by Francesco Castelli; Antonio Raudino; Salvatore Gurrieri
No coin nor oath required. For personal study only.
An analysis of Ca 2 + influence on the thermotropic behaviour of different phosphatidylcholine-vitamin D~ mixtures was carried out by differential scanning calorimetry technique (DSC). A competitive effect between Ca 2 -and vitamin D 3 on the membrane fluidity was detected. The observed shifts of the gel-liquid crystal transition temperature were correlated with the mole fraction of vitamin D~ dissolved within the lipid bilayer as well as with the Ca z + concentration in the surrounding medium. These shifts were rationalized on the ground of a simple microscopic model through the calculation of the internal pressure exerted by the adsorbed Ca -'~ on the lipid matrix by the Clapeyron equation. The experimental results and the obtained equations accord with each other and support the idea of micro-domain formation richer in one lipid component. The extent of such lateral phase separation of the lipid components seems to be favoured by the adsorption of Ca 2 + at the membrane-water interface.
π SIMILAR VOLUMES
The course of systemic lupus erythematosus (SLE), an autoimmune disease, is markedly affected by hormones such as estrogen and prolactin. It is well known that heavy exposure to sunlight has deleterious effects on SLE, triggering episodes of the disease. Classical explanations for this occurrence su