Membrane lipid aggregate structures

The dyes that bind to biomembranes are often designed to contain the polar head (that is often a chromophore) and long aliphatic tails. Being thus similar to that of the membrane-forming lipids, this structure favors their insertion into the membrane. At the same time, such dyes could form J-aggregates when available in the membrane at sufficient dye to lipid concentration ratios (Fig. 4). 

If preparative or instrumental artifact is ruled out, the universal occurrence of red-shifted Cotton effects with a-helical character in all the membranes studied points to a common property of the proteins in biological membranes. The ORD results from lipid-free mitochondrial structural protein and erythrocyte ghost protein are consistent with assigning the red shift in these membranes to aggregated protein. It is, therefore, reasonable that similar protein-protein association may occur in all membranes. Ionic requirements for membrane stability could then reflect in part the requirements for protein-protein association. To some extent the molecular associations which stabilize membranes, therefore, may be protein-protein as well as lipid-lipid in nature. 

Lipid bilayer The structure of biological membranes in which the hydrophobic tails of lipids aggregate in two layers. 

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