Abstract：
:A new series of negatively charged, paramagnetic alkylsulfonate probes was synthesized and can be used to measure both the internal and the external surface potentials of model membrane systems. We tested for discreteness-of-charge effects in lipid membranes by comparing the surface potentials, estimated by use of these negatively charged amphiphiles, with that of a series of positively charged alkylammonium nitroxides in charged membranes. From the partitioning of these probes, the membrane surface potential was estimated in phosphatidylcholine membranes containing either phosphatidylserine or didodecyldimethylammonium bromide. The surface potentials, estimated with either positive or negative probes, were identical, within experimental error, in either positive or negative membranes, and they were well accounted for by a simple Gouy-Chapman-Stern theory. This symmetry, with respect to the sign of the charge, indicates that discreteness-of-charge effects are not significant in determining the potential-sensitive phase partitioning of these probes in model membranes. Thus, despite the fact that charge on membranes is discrete, models that assume a uniform density of charge in the plane of the membrane adequately account for the potentials measured by these amphiphilic probes.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Hartsel SC,Cafiso DSdoi
10.1021/bi00373a014subject
Has Abstractpub_date
1986-12-16 00:00:00pages
8214-9issue
25eissn
0006-2960issn
1520-4995journal_volume
25pub_type
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