Headgroups hydrated

The monomer to inverse micelle transition of dodecylammonium propionate (DAP) in CH2G2 was monitored by tire shifts in the COO bands. Addition of water caused further decreases in the COO- band frequency due to headgroup hydration. Micelle formation in hexane yielded similar spectroscopic changes (83). Frequency shifts induced by hydrogen bonding to water in the inverse micelle core were illustrated for phosphonate, carboxylate, and sulfate headgroups (84). 

Bayerl, T. M., Thomas, R. K., Penfold, J., Rennie, A. and Sackmann, E. (1990). Specular reflection of neutrons at phospholipid monolayers. Changes of mono-layer structure and headgroup hydration at the transition from expanded to the condensed phase. Biophys. J. 57 1095-1098. 

The lamellar gel-lamellar liquid-crystalline (L - L ) phase transition, frequently also referred to as (chain-)melting, order-disorder, solid-fluid, or main transition, is the major energetic event in the lipid bilayers and takes place with a large enthalpy change. It is associated with rotameric disordering of the hydrocarbon chains, increased headgroup hydration, and increased... 

Cevc, G., Watts, A., and Meu sh, D., 1981, Titration of the phase transition of phosphatidylserine bilayer membranes. Effects of pH surface electrostatics, ion binding and headgroup hydration, Biochemistry, 20 4955. 

Sodium octanoate (NaO) forms reversed micelles not only in hydrocarbons but also in 1-hexanol/water. The hydration of the ionogenic NaO headgroups plays an important role in this case too. For this reason Fujii et al. 64) studied the dynamic behaviour of these headgroups and the influence of hydration-water with l3C and 23Na NMR measurements. Below w0 = [H20]/[NaO] 6 the 23Na line-width... 

Biomembranes mainly consists of phospholipid matrices, and the major component is phosphorylcholines (PC). PC is an amphiphile consisting of hydrophilic headgroup and hydrophobic long chains. In view of the amphiphilic feature of PC, we can divide hydrated lipid bilayers into the three zones, I, II, and III. The zone model, which has been used in a recent NMR study of DD [46-48], is illustrated in Fig. 2. 

Considering only the lipid phase as the transport pathway for the peptide, as the solute enters and diffuses across the membrane it will encounter a number of different microenvironments. The first is the aqueous membrane interface (Fig. 23). In this region, the hydrated polar headgroups of the membrane phospholipids separate the aqueous phase from the apolar membrane interior. It has been shown that this region is capable of satisfying up to 70% of the hydrophobic effect... 

Water molecules are absent from the hydrophobic interior, but both the choline and the phosphate headgroups are fully solvated [41]. Similarly, the first hydration shell of the sulfate headgroup of SDS is formed rather by water molecules than by sodium ions. Because of hydration the charge density due to the lipid headgroups is overcompensated by the water dipoles, thereby reducing the transmembrane potential by 50-100 mV across the lipid water interface and resulting in a negative potential at the aqueous side [42]. 

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