The permeability properties of planar lipid bilayers made from egg lecithin, n-decane and a long-chain secondary amine (n-lauryl [trialkylmethyl]amine) are described. Membranes containing the secondary amine show halide selectivity and high conductance at pH less than 6, as estimated by measurements of zero-current potentials generated by NaBr activity gradients. In the absence of halide ions, the membranes show H+ selectivity, although the total membrane conductance is relatively low. In 0.1 M NaBr both the membrane conductance (Gm) and the Br- self-exchange flux (JBr) are proportional to H+ concentration over the pH range of 7 to 4, and both JBr and Gm saturate at pH less than 4. However, JBr is always more than 100 times the flux predicted from Gm and the transference number for Br-. Thus, greater than 99% of the observed (tracer) flux is electrically silent and is not a Br2 or HBrO flux because the reducing agent, S2O3=, has no effect on JBr. At pH 7, JBr is proportional to Br- concentration over the range of 1-340 mM, with no sign of saturation kinetics. Both urea and sulfate tracer permeabilities are low and are unaffected by pH. The results can be explained by a model in which the secondary amine behaves as a monovalent, titratable carrier which exists in three chemical forms (C, CH+, and CHBr). Br- crosses the membrane primarily as the neurtal complex (CHBr). The positively charged carrier (CH+) crosses the membrane slowly compared to CHBr, but CH+ is the principal charge carrier in the membrane. At neurtal pH greater than 99% of the amine is in the nonfunctional form (C), which can be converted to CH+ or CHBr by increasing the H+ or Br- concentrations. The permeability properties of these lipid bilayers resemble in many respects the permeability properties of red cell membranes.
Skip Nav Destination
Article navigation
1 March 1978
Article|
March 01 1978
Electrically silent anion transport through lipid bilayer membranes containing a long-chain secondary amine.
J Gutknecht
J S Graves
D C Tosteson
Online ISSN: 1540-7748
Print ISSN: 0022-1295
J Gen Physiol (1978) 71 (3): 269–284.
Citation
J Gutknecht, J S Graves, D C Tosteson; Electrically silent anion transport through lipid bilayer membranes containing a long-chain secondary amine.. J Gen Physiol 1 March 1978; 71 (3): 269–284. doi: https://doi.org/10.1085/jgp.71.3.269
Download citation file:
Sign in
Don't already have an account? Register
Client Account
You could not be signed in. Please check your email address / username and password and try again.
Could not validate captcha. Please try again.
Sign in via your Institution
Sign in via your InstitutionSuggested Content
The Permeability of Thin Lipid Membranes to Bromide and Bromine
J Gen Physiol (April,1972)
Ionic Permeability of Thin Lipid Membranes : Effects of n-alkyl alcohols, polyvalent cations, and a secondary amine
J Gen Physiol (March,1970)
A PERFUSING SOLUTION FOR THE LOBSTER (HOMARUS) HEART AND THE EFFECTS OF ITS CONSTITUENT IONS ON THE HEART
J Gen Physiol (September,1941)
Email alerts
Advertisement