Assemblies of synthetic sphingolipids form ordered aqueous pathways through membranes

ORGN 42

Marco Colombini, colombini@umd.edu and Leah J. Siskind, lsiskind2001@yahoo.com. Biology, University of Maryland, College Park, MD 20742
Both N-acetyl-D-erythro-sphingosine (C2-ceramide) and N-palmitoyl-D-erythro-sphingosine (C16-ceramide) self-assemble in phospholipid membranes to form highly organized cylindrical structures that span the membrane allowing solutes and small proteins to cross the membrane by free diffusion. These large aqueous pathways are thought to be formed by a variable number of columns acting as the staves of a barrel. These columns, consisting of 6 monomers hydrogen-bonded together, are thought to pre-assemble in the membrane before inserting as units into a pre-existing channel. Indeed, these channels are dynamic, growing or shrinking in size in a stochastic manner usually through discrete changes in conductance. Critical structural features of ceramide, are the 4,5 trans double bond on the sphingoid base backbone and the amide linkage between this base and the N-linked fatty-acyl chain. No channels are observed without the double bond and sphingosine alone is only capable of forming relatively small channels (2 nm in diameter).
 

Membrane Active, Synthetic Organic Compounds
1:30 PM-5:05 PM, Sunday, 28 August 2005 Washington DC Convention Center -- Ballroom C, Oral

Division of Organic Chemistry

The 230th ACS National Meeting, in Washington, DC, Aug 28-Sept 1, 2005