Reversible inactivation of serpins at acidic pH.

The inhibitory activity of the serpins alpha(1)-proteinase inhibitor, alpha(1)-antichymotrypsin, alpha(2)-antiplasmin, antithrombin and C(1)-esterase inactivator is rapidly lost at pH 3 but slowly recovers at pH 7.4 with variable first-order rates (t(1/2)=1.4-19.

A novel type of membrane based on cholesteryl phosphocholine, cholesteryl phosphate, or sitosteryl phosphate, and dimyristoylglycerol.

Mixtures of amphiphilic cholesteryl phosphate (CP), sitosteryl phosphate (SP), or cholesteryl phosphocholine (CPC) with the nonphosphoryl diacyl lipid dimyristoylglycerol (DMG) or with cholesterol give self-organized systems (giant vesicles) in a wide range of pH, as demonstrated by fluorescence microscopy, differential scanning calorimetry, and small-angle X-ray scattering. The water permeability of a 1 : 1 molar mixture of CPC and DMG was also measured by a stopped-flow/light-scattering method. The novel self-organized systems are akin to natural eukaryotic ones, the only difference being the site of the phosphate-containing head-group, located on cholesterol instead of DMG.

A novel type of membranes based on cholesteryl phosphate.

Mixtures of the rigid amphiphile disodium cholesteryl phosphate (DCP) with the non-phosphorylated diacyl amphiphile dimyristoylglycerol (DMG) give self-organized systems in a wide range of pH, as demonstrated by differential microcalorimetry. These systems can be closed bilayer vesicles, as shown by optical microscopy (Nomarski and confocal). Neither DMG nor DCP, taken alone, give vesicles in these conditions but 10% DMG is enough to lead to the formation of vesicles from pH 5.

Behaviour of Pluronic P84 block copolymer micelles above the gelification temperature as probed by positron annihilation lifetime spectroscopy.

The new method based on positron annihilation lifetime spectroscopy (PALS) to determine both the mean core radius, R(core), and aggregation number, N(ag), of micelles is applied to the study of aqueous solutions of the triblock Pluronic P84 copolymer as a function of temperature (T), beyond the gelification point (334 K). Two long-lived components appear in the PALS spectra, ascribed to triplet positronium in the water bulk (o-Ps(aq)) and in the organic core of the micelles (o-Ps(org)). Of the various fitting parameters, only the lifetime of the latter species, tau4, and the micellar parameters, R(core) and N(ag), disclose the occurrence of gelification by first increasing up to 334 K, then decreasing.