The Study on the Preparation and Characterization of Crosslinked Polyvinyl Alcohol Microspheres

2013 ◽  
Vol 716 ◽  
pp. 337-342
Author(s):  
Yun Feng Yang ◽  
Bao Jiao Gao ◽  
Su Yu Liu
Keyword(s):  
Particle Size ◽  
Polyvinyl Alcohol ◽  
Crosslinking Agent ◽  
Influence Factors ◽  
Microemulsion Polymerization ◽  
Reaction Conditions ◽  
The Matrix ◽  
Inverse Microemulsion ◽  
Inverse Microemulsion Polymerization

Linear polyvinyl alcohol ( PVA ) as the matrix, Glutaraldehyde as crosslinking agent, the crosslinked polyvinyl alcohol microspheres ( CPVA ) was prepared by inverse microemulsion polymerization. Influence factors for forms and particle size of crosslinking spheres such as the ratio of oil and water, reaction temperature and time, crosslinking agent and catalyst use level, stirring speed. When reaction conditions changed, the particle size would change accordingly.

Thermoresponsive nanostructured poly(N-isopropylacrylamide) hydrogels made via inverse microemulsion polymerization

2005 ◽  
Vol 284 (4) ◽  
pp. 387-395 ◽  
Author(s):  
V. V. A. Fernandez ◽  
N. Tepale ◽  
J. C. Sánchez-Díaz ◽  
E. Mendizábal ◽  
J. E. Puig ◽  
...  
Keyword(s):  
Microemulsion Polymerization ◽  
Inverse Microemulsion ◽  
Inverse Microemulsion Polymerization

Synthesis of Cationic Polyelectrolytes by Inverse Microemulsion Polymerization

2009 ◽  
Vol 30 (23) ◽  
pp. 2036-2041 ◽  
Author(s):  
Gemma González ◽  
Jesus M. Ugalde ◽  
José C. de la Cal ◽  
José M. Asua
Keyword(s):  
Microemulsion Polymerization ◽  
Inverse Microemulsion ◽  
Cationic Polyelectrolytes ◽  
Inverse Microemulsion Polymerization

scholarly journals Structure and Mechanism of Human UDP-glucose 6-Dehydrogenase

2011 ◽  
Vol 286 (27) ◽  
pp. 23877-23887 ◽  
Author(s):  
Sigrid Egger ◽  
Apirat Chaikuad ◽  
Kathryn L. Kavanagh ◽  
Udo Oppermann ◽  
Bernd Nidetzky
Keyword(s):  
Active Site ◽  
Quaternary Structure ◽  
Binding Domain ◽  
Side Chain ◽  
Reaction Conditions ◽  
Epithelial Tumor ◽  
Coenzyme Binding ◽  
Ternary Complex Formation ◽  
The Matrix

Elevated production of the matrix glycosaminoglycan hyaluronan is strongly implicated in epithelial tumor progression. Inhibition of synthesis of the hyaluronan precursor UDP-glucuronic acid (UDP-GlcUA) therefore presents an emerging target for cancer therapy. Human UDP-glucose 6-dehydrogenase (hUGDH) catalyzes, in two NAD+-dependent steps without release of intermediate aldehyde, the biosynthetic oxidation of UDP-glucose (UDP-Glc) to UDP-GlcUA. Here, we present a structural characterization of the hUGDH reaction coordinate using crystal structures of the apoenzyme and ternary complexes of the enzyme bound with UDP-Glc/NADH and UDP-GlcUA/NAD+. The quaternary structure of hUGDH is a disc-shaped trimer of homodimers whose subunits consist of two discrete α/β domains with the active site located in the interdomain cleft. Ternary complex formation is accompanied by rigid-body and restrained movement of the N-terminal NAD+ binding domain, sequestering substrate and coenzyme in their reactive positions through interdomain closure. By alternating between conformations in and out of the active site during domain motion, Tyr14, Glu161, and Glu165 participate in control of coenzyme binding and release during 2-fold oxidation. The proposed mechanism of hUGDH involves formation and breakdown of thiohemiacetal and thioester intermediates whereby Cys276 functions as the catalytic nucleophile. Stopped-flow kinetic data capture the essential deprotonation of Cys276 in the course of the first oxidation step, allowing the thiolate side chain to act as a trap of the incipient aldehyde. Because thiohemiacetal intermediate accumulates at steady state under physiological reaction conditions, hUGDH inhibition might best explore ligand binding to the NAD+ binding domain.

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