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Phase behavior of isolated photoreceptor membrane lipids is modulated by bivalent cations
Author(s) -
Mollevanger Leo C.P.J.,
De Grip Willem J.
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)80329-4
Subject(s) - bivalent (engine) , chemistry , membrane , bilayer , biophysics , crystallography , phase transition , aqueous solution , lipid bilayer , biochemistry , organic chemistry , biology , metal , thermodynamics , physics
The phase behavior of isolated photoreceptor membrane lipids is further investigated by 31 P‐NMR, in view of earlier discrepant results [(1979) Biochim. Biophys. Acta 558, 330–337; (1982) FEBS Lett. 124, 93–99]. We present evidence that the discrepancy is due to bivalent cations. When resuspended in aqueous media at neutral pH in the absence of bivalent cations, the isolated photoreceptor membrane lipids largely adopt the bilayer configuration. However, upon addition of such cations (Ca 2+ Mg 2+ ) or when resuspended in their presence, the formation of other phases (hexagonal H II , lipidic particles) results. The rate of this transition depends on cation concentration and temperature. The transition is not easily reversed by addition of EDTA. Implications with regard to photoreceptor membrane structure and function need further study.