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Hydrophilic Domains (hydrophilic + domain)

Distribution by Scientific Domains
Polymers and Materials Science50%

Selected Abstracts

Chaperone-like activities of different molecular forms of ,-casein.

BIOPOLYMERS, Issue 8 2009
Importance of polarity of N-terminal hydrophilic domain
Abstract As a member of intrinsically unstructured protein family, ,-casein (,-CN) contains relatively high amount of prolyl residues, adopts noncompact and flexible structure and exhibits chaperone-like activity in vitro. Like many chaperones, native ,-CN does not contain cysteinyl residues and exhibits strong tendencies for self-association. The chaperone-like activities of three recombinant ,-CNs wild type (WT) ,-CN, C4 ,-CN (with cysteinyl residue in position 4) and C208 ,-CN (with cysteinyl residue in position 208), expressed and purified from E. coli, which, consequently, lack the phosphorylated residues, were examined and compared with that of native ,-CN using insulin and alcohol dehydrogenase as target/substrate proteins. The dimers (,-CND) of C4-,-CN and C208 ,-CN were also studied and their chaperone-like activities were compared with those of their monomeric forms. Lacking phosphorylation, WT ,-CN, C208 ,-CN, C4 ,-CN and C4 ,-CND exhibited significantly lower chaperone-like activities than native ,-CN. Dimerization of C208 ,-CN with two distal hydrophilic domains considerably improved its chaperone-like activity in comparison with its monomeric form. The obtained results demonstrate the significant role played by the polar contributions of phosphorylated residues and N-terminal hydrophilic domain as important functional elements in enhancing the chaperone-like activity of native ,-CN. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 623,632, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]

Synthesis and characterization of proton-conducting copolyimides bearing pendant sulfonic acid groups

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2005
Yan Yin
Abstract A series of sulfonated copolyimides (co-SPIs) bearing pendant sulfonic acid groups were synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), bis(3-sulfopropoxy) benzidines (BSPBs), and common nonsulfonated diamines via statistical or sequenced polycondensation reactions. Membranes were prepared by casting their m -cresol solutions. The co-SPI membrane had a microphase-separated structure composed of hydrophilic and hydrophobic domains, but the connecting behavior of hydrophilic domains was different from that of the homo-SPIs. The co-SPI membranes displayed clear anisotropic membrane swelling in water with negligibly small dimensional changes in the plane direction of the membrane. With water uptake values of 39,94 wt %, they showed dimensional changes in membrane thickness of about 0.11,0.58, which were much lower than those of homo-SPIs. The proton conductivity , values of co-SPI membranes with ion exchange capacity values ranging from 1.95,2.32 meq/g increased sigmoidally with increasing relative humidity. They displayed , values of 0.05,0.16 S/cm at 50 °C in liquid water. Increasing temperature up to 120 °C resulted in further increase in proton conductivity. The co-SPI membranes showed relatively good conductivity stability during the aging treatment in water at 100 °C for 300 h. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1545,1553, 2005 [source]

Correlation between Morphology, Water Uptake, and Proton Conductivity in Radiation-Grafted Proton-Exchange Membranes

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2010
Sandor Balog
Abstract An SANS investigation of hydrated proton exchange membranes is presented. Our membranes were synthesized by radiation-induced grafting of ETFE with styrene in the presence of a crosslinker, followed by sulfonation of the styrene. The contrast variation method was used to understand the relationship between morphology, water uptake, and proton conductivity. The membranes are separated into two phases. The amorphous phase hosts the water and swells upon hydration, swelling being inversely proportional to the degree of crosslinking. Hydration and proton conductivity exhibit linear dependence on swelling. Proton conductivity and volumetric fraction of water are related by a power law, indicating a percolated network of finely dispersed aqueous pores in the hydrophilic domains. [source]

Chaperone-like activities of different molecular forms of ,-casein.

BIOPOLYMERS, Issue 8 2009
Importance of polarity of N-terminal hydrophilic domain
Abstract As a member of intrinsically unstructured protein family, ,-casein (,-CN) contains relatively high amount of prolyl residues, adopts noncompact and flexible structure and exhibits chaperone-like activity in vitro. Like many chaperones, native ,-CN does not contain cysteinyl residues and exhibits strong tendencies for self-association. The chaperone-like activities of three recombinant ,-CNs wild type (WT) ,-CN, C4 ,-CN (with cysteinyl residue in position 4) and C208 ,-CN (with cysteinyl residue in position 208), expressed and purified from E. coli, which, consequently, lack the phosphorylated residues, were examined and compared with that of native ,-CN using insulin and alcohol dehydrogenase as target/substrate proteins. The dimers (,-CND) of C4-,-CN and C208 ,-CN were also studied and their chaperone-like activities were compared with those of their monomeric forms. Lacking phosphorylation, WT ,-CN, C208 ,-CN, C4 ,-CN and C4 ,-CND exhibited significantly lower chaperone-like activities than native ,-CN. Dimerization of C208 ,-CN with two distal hydrophilic domains considerably improved its chaperone-like activity in comparison with its monomeric form. The obtained results demonstrate the significant role played by the polar contributions of phosphorylated residues and N-terminal hydrophilic domain as important functional elements in enhancing the chaperone-like activity of native ,-CN. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 623,632, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source]