Cooperative Binding at Lipid Bilayer Membrane Surfaces

Abstract

The binding of copper(II) ions to membrane-bound synthetic receptors has been investigated. Complexation fitted a 4:1 receptor:copper(II) model, and the observed binding constants are significantly enhanced at the membrane relative to solution; these effects can be explained by the lower polarity of the membrane-water interface and the concentrating effect of the membrane, with no observed contribution from receptor preorganization. The stoichiometry of the complex formed is very sensitive to the concentration of the receptor in the membrane, and at low concentrations, binding is reduced relative to solution controls. This implies that by increasing or decreasing the number of receptors in their membranes, cells can finely tune biological responses such as chemotaxis that depend on the size of the receptor-ligand clusters formed.

Intravesicular and intervesicular interaction by orthogonal multivalent host–guest and metal–ligand complexation

“…N-nitrilotriacetic acidfunctionalized lipids (22,23) and SAMs (24,25) have been used to immobilize proteins through multivalent interactions. In a comparable approach, the multivalent binding of Cu(II) ions to a membrane-bound dansyl-ethylenediamine conjugate (26) and of Zn(II) to a membrane-embedded dipicolylamine receptor (27) has been reported.…”

Dynamic combinatorial chemistry at the phospholipid bilayer interface

“…These global concentrations are, however, unlikely to be reflected by the local concentrations of the thiols in the vicinity of the lipid bilayer interface where thioester exchange is taking place. The microenvironment created by the lipids is considerably less polar than bulk solution [63][64][65], thus disfavouring the recruitment of more polar species such as negatively charged 4 and 7 to the lipid bilayer interface, presumably due to costly desolvation.…”

Design of Fluorescent Materials for Chemical Sensing

“…57, 61 Yang and co-workers recently reported the immobilization of pyrene-labeled metalloporphyrins in a plastized poly(vinyl chloride) (PVC) membrane for the sensing of imidazole derivatives such as histidine. 62 Approaches based on dye-doped thin films have been used in the analysis of organic vapors, [63][64][65] the detection of metal ions, [66][67][68] and the determination of pH. 69,70 Processing of polymers can also yield polymeric particles with sizes ranging from nanometers to micrometers.…”

“…They estimated that a single metal ion produced the quenching of 44 dye molecules. 63,99,234 Tonellato and co-workers modified silica nanoparticles via the reaction of commercially available silica nanoparticles with average size of 18 nm with a trimethoxysilane derivatized dansylamide as reporter and a picolinamide as Cu 2+ binding subunit. 77 In this case receptor and fluorophores are not bound together but the spatial proximity is ensured by selfassembly of the sensing elements.…”