Modified expression of coagulation factor VIII by addition of a glycosylation site at the N terminus of the protein.

Recently, it was shown that glycoproteins with N-glycans close to the NH(2) terminus can directly enter the calnexin/calreticulin cycle and bypass BiP binding. This should allow efficient secretion of glycoproteins such as factor VIII (FVIII) whose secretion is negatively affected by BiP interaction. Examination of the glycosylation pattern of the NH(2) terminus of FV and FVIII revealed N-glycans at positions 23 and 27 in FV and at position 41 in FVIII. To improve FVIII secretion, a 14-amino-acid-long polypeptide with (G3) or without (G0; control) three N-linked glycosylation consensus sites was inserted upstream of the NH(2) terminus of a B-domain deleted FVIII protein. Expression of G3- and G0-constructs in three different cell lines resulted in the same or even higher expression rate of protein as found for the B-domain deleted FVIII. However, as demonstrated by Western blot analysis, the G3- as well as the G0-protein variants were mainly retained inside the cells in similar amounts. Thus, glycosylation alone does not automatically lead to higher secretion rates, but must be in context to the normal structure of the FVIII protein.

Structure and texture of anisotropic nematic gels.

Anisotropic nematic gels are prepared via in situ polymerization of diacrylate monomers in an oriented nematic liquid crystal (LC) matrix. The structure of the gels is studied from micrometer to nanometer scales by optical microscopy, small angle neutron scattering, and theta/2theta light scattering. A strong anisotropy is evidenced at all scales without electric field for both mesogenic and nonmesogenic monomers. The gel network can be pictured as an ordered but strongly distorted and polydisperse structure with two characteristic sizes: the mean size of the polymer objects and a correlation length between these objects, corresponding to the mean-size of the LC domains, which are estimated from neutron and light scattering results to be of the order of some tens of nanometers and some micrometers, respectively. Moreover, a sheet-like structure of the polymer network is evidenced. When an electric field is applied, one part of the LC switches while the other part remains anchored to the polymer network. The electric field dependence of the volume fraction of anchored LC is estimated from the analysis of the light scattering data. We emphasize systematic correlations between structure and electro-optical properties of the gels.

Switching behavior and electro-optical properties of liquid crystals in nematic gels

Anisotropic nematic gels are prepared via in situ polymerization of diacrylate monomers in an orientated nematic liquid crystal (LC) matrix. The switching behavior of the LC molecules under electric field is probed in polarized Raman spectroscopy and straight theta-2straight theta elastic light scattering experiments. The electro-optical characteristics of the gels are directly related to the electric field dependence of the fraction of switched molecules. The electro-optical contrast relates to the coexistence of switched LC domains and LC domains anchored to the polymer network.