Mixed vesicles

Figure 10.15 Intensity-weighted size distribution of POPC in 0.2 M bicine buffer solution, pH 8.5 0.5 ml solution of 1 mM 30 nm extruded POPC vesicles mixed with 0.5 ml solution of 1 mM 200 nm extruded POPC vesicles. The measuring angle is 90°. (From Cheng and Luisi, 2003.)...

Single-compartment DHP vesicles Mixed Cd-ZnS particles prepared in situ in vesicles from mixtures of Cd2+ and Zn2+ by H2S... 

Indirect sympathomimetics cause norepinephrine release from presynaptic terminals, but do not bind to adrenergic receptors (Fig. 2.5, Table 2.1B). These drugs enter the presynaptic terminal and displace stores of norepinephrine from storage vesicles. Mixed sympathomimetics displace norepinephrine from presynaptic terminals and bind to adrenergic receptors. (Fig. 2.5, Table 2.1B). 

Small micelles in dilute solution close to the CMC are generally beheved to be spherical. Under other conditions, micellar materials can assume stmctures such as oblate and prolate spheroids, vesicles (double layers), rods, and lamellae (36,37). AH of these stmctures have been demonstrated under certain conditions, and a single surfactant can assume a number of stmctures, depending on surfactant, salt concentration, and temperature. In mixed surfactant solutions, micelles of each species may coexist, but usually mixed micelles are formed. Anionic-nonionic mixtures are of technical importance and their properties have been studied (38,39). 

A number of recent studies consider more complex systems, such as freezing vesicles [246] (freezing can be induced by reducing the tether length) or mixed membranes which contain more than one component [247,248]. The possibility that a membrane may break up and form pores has also been considered [249]. 

Preparation of monodisperse vesicles with variable size by dilution of mixed micellar solutions of bile salt and phosphatidylcholine, Biochim. Biophys. Acta, 775. 111-114. 

Researchers studying polypeptide and polypeptide hybrid systems have also processed vesicles using two solvents. This method usually involves a common organic solvent that solubilizes both blocks and an aqueous solvent that solublizes only the hydrophilic block. The two solvents can be mixed with the polypeptide or polypeptide hybrid system at the same time or added sequentially. The choice of organic solvent depends heavily upon the properties of the polypeptide material, and commonly used solvents include dimethylformamide (DMF) [46, 59], methanol (MeOH) [49], dimethyl sulfoxide (DMSO) [50, 72], and tetrahydrofuran (THF) [44, 55]. Vesicles are usually formed when the organic solvent is slowly replaced with an aqueous solution via dialysis or removed through evaporation however, some vesicles have been reported to be present in the organic/aqueous mixture [49]. 

NC6H40)2P0.0Et + hydroxamates Dephosphorylations by mixed micelles, vesicles and hydrophobic hydroxamic acid compared Okahata et al., 1981... 

The mixing of nematogenic compounds with chiral solutes has been shown to lead to cholesteric phases without any chemical interactions.147 Milhaud and Michels describe the interactions of multilamellar vesicles formed from dilauryl-phosphotidylcholine (DLPC) with chiral polyene antibiotics amphotericin B (amB) and nystatin (Ny).148 Even at low concentrations of antibiotic (molar ratio of DLPC to antibiotic >130) twisted ribbons are seen to form just as the CD signals start to strengthen. The results support the concept that chiral solutes can induce chiral order in these lyotropic liquid crystalline systems and are consistent with the observations for thermotropic liquid crystal systems. Clearly the lipid membrane can be chirally influenced by the addition of appropriate solutes. 

When, the vesicles which contain the catalyst and the substrate separately are mixed at low pH, substrate transfer occurs without the catalytic reaction (The protonated imidazole is inactive). The rate constant of substrate transfer... 

Ma G, Cheng Q (2006) Manipulating fret with polymeric vesicles development of a mix-and-detect type fluorescence sensor for bacterial toxin. Langmuir 22 6743-6745... 

The 31P n.m.r. of phospholipids has been the subject of a number of papers.62-89 These have been primarily aimed at investigating the conformation and motion of phospholipids in bilayers, but information has also been obtained on gel-to-liquid crystal transformations of phospholipids.65-67 A P31 1H nuclear Overhauser effect indicates that there is little tendency for mixed phosphatidylcholine/phosphatidyl-ethanolamine vesicles to segregate in separate domains.68 69 A phosphonium analogue (23) of choline chloride has been prepared and converted chemically into... 

---