Partition of DDE in synthetic and native membranes determined by ultraviolet derivative spectroscopy

• Published in: Biochimica et biophysica acta 1995-08, Vol.1238 (1), p.22-28
• Main Authors: Videira, Romeu A., Antunes-Madeira, Maria do Carmo, Custódio, JoséB.A., Madeira, Vítor M.C.
• Format: Article
• Language: English
• Subjects: Cholesterol - metabolism; DDE; Dichlorodiphenyl Dichloroethylene - metabolism; Fluidity; Lipid Bilayers - metabolism; Model membrane; Native membrane; Partition coefficient; Phospholipids - metabolism; Spectrophotometry, Ultraviolet; Temperature
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/0005-2736(95)00102-9

Partition coefficients of DDE (2,2-bis( p-chlorophenyl)-1,1-dichloroethylene) were determined, in model and native membranes, as a function of temperature, lipid chain length, cholesterol content and DDE concentration, by means of second derivative ultraviolet spectrophotometry. DDE incorporation increases with the temperature, since the partition values in dimyristoylphosphatidylcholine (DMPC), at 24, 30 and 37°C, are 5722 ± 138, 10 356 ± 763 and 14 006 ± 740, respectively. The insecticide incorporates better into bilayers of DMPC as compared with DPPC (dipalmitoylphosphatidylcholine). The partition decreases from 10 355 ± 763 in DMPC to 6432 ± 613 in DPPC, at temperatures 5–7°C above the midpoint of their transitions. The addition of cholesterol to fluid membranes of DMPC depresses the partition of DDE. In agreement with the results in models of synthetic lipids, the partition of DDE into native membranes increases with the temperature and decreases with the intrinsic cholesterol. It is concluded that a fluid membrane favors the accumulation of DDE.