Proteins, polyions

Rusling, J.F. Electroactive and Enzyme-Active Protein Polyion Films Assembled Layer-by-Layer. 

Direct Voltammetry Using Layered Protein-polyion Films... 

A. Films Cast from Protein-Polyion Mixtures... 

Improved catalysis of styrene epoxidation by protein-polyion films was related to their better mechanical stability compared to the surfactant films. Product stereochemistry for the epoxidation of cw- 3-methylstyrene depended on oxygen availability. There appear to be two pathways for olefin oxidation. The stereoselective pathway utilizes the high valent iron-oxygen intermediate (Figure 24), as does the natural enzyme system. The non-stereoselective pathway may involve a peroxyl radical near the protein surface that forms in the presence of oxygen [91]. The competing reactions are summarized in Figure 26. 

Ion exchange is actually a far more complicated process than the simple exchange of one cation for another or one anion for another, particularly for complex polyions such as proteins and oligonucleotides. Each ion of the stationary or mobile phase is surrounded by a cluster of counterions and water. When an ion in the mobile phase is transferred to the stationary phase, the cluster of counterions and water surrounding it is partially or completely displaced. A similar event occurs at the binding site of the stationary phase. Ions displaced from the stationary phase undergo the converse process. The... 

Cacia, J., Quan, C. P., Vasser, M., Sliwkowski, M. B., and Frenz, J., Protein sorting by high-performance liquid chromatography I. Biomimetic interaction chromatography of recombinant human deoxyribonuclease I on polyionic stationary phases, /. Chromatogr., 634, 229, 1993. 

Polyelectrolyte complexes formed by polyion pairing are of special interest, including protein-polyelectrolyte interactions such as protein-DNA complexes. A special case of polyelectrolyte complexes are polyelectrolyte multilayers (PEM) on surfaces formed by ion pairing, van der Waals interactions and counterion release of oppositely charged polyelectrolytes [2, 3]. 

A novel capillary electrophoresis method using solutions of non-crosslinked PDADMAC is reported to be effective in the separation of biomolecules [211]. Soil studies conducted with PDADMAC report the minimization of run-off and erosion of selected types of soils [212]. In similar studies, PDADMAC has found to be a good soil conditioner [213]. The use of PDADMAC for the simultaneous determination of inorganic ions and chelates in the kinetic differentiation-mode capillary electrophoresis is reported by Krokhin [214]. Protein multilayer assemblies have been reported with the alternate adsorption of oppositely charged polyions including PDADMAC. Temperature-sensitive flocculants have been prepared based on n-isopropylacrylamide and DADMAC copolymers [215]. A potentiometric titration method for the determination of anionic polyelectrolytes has been developed with the use of PDADMAC, a marker ion and a plastic membrane. The end-point is detected as a sharp potential change due to the rapid decrease in the concentration of the marker due to its association with PDADMAC [216]. 

Vinogradov, S., Batrakova, E., Li, S. and Kabanov, A. (1999a) Polyion complex micelles with protein-modified corona for receptor-mediated delivery of oligonucleotides into cells. Bioconjug. Chem., 10, 851-860. 

This polyionic structure can provide protection against HIV infection by binding to the gpl20 glycoprotein receptor on the vims surface. The normal course of infection of healthy cells with HIV begins when the gpl20 protein on the surface of the vims binds to the CD4 receptor on the surface of the healthy cell [71b]. 

The main conclusion drawn from the simulations [170] is that in the presence of monovalent counterions, the charged protein-like copolymers can be soluble, even in a very poor solvent for hydrophobic units. There are three temperature regimes, which are characterized by different spatial organization of polyions and their conformational behavior. 

Tonegawa et al. (2004) created a cationic polylysine with a tetrapeptide end sequence (glycine-tyrosine-glycine-lysine), which is a motif common to the consensus sequences of mussel adhesive proteins. They then cross-linked this with the anionic polysaccharide, gellan, enzymatically. The polyionic complexation between the cationic peptide and the anionic polysaccharide formed a hybrid fiber at the aqueous solution interface that, when cross-linked, mimicked the byssus gel that marine mussels use to adhere to surfaces, despite the presence of water and salt. 

Preparation of enzyme-DNA films one layer at a time provides excellent control over the thickness of films designed to the specifications of the builder. Films containing two layers each of enzyme and DNA that are 20-40 nm thick are easily made. Alternate adsorption of layers of biomolecules and polyions is a general method that has been developed over the past decade by Lvov et al.[17 201 The technique has been used to make ultrathin films of a wide variety of proteins and oppositely charged... 

Proteins and Polyions. In Protein Architecture Interfacing Molecular Assemblies and Immobilization Biotechnology, Lvov, Y., Mohwald, H., Eds. ... 

Lvov, Y. Thin-Film Nanofabrication by Alternate Adsorption of Polyions, Nanoparticles, and Proteins. 34. In Handbook of Surfaces and Interfaces of Materials Nalwa, R.W., Ed. Nanostructured Materials,... 

The titration of protein with polymer, shown in Figure 6, exhibits very different features than the titration curve of Figure 5. Turbidity appears at once and, initially, exhibits a linear dependence on PDMDAAC concentration. The rate of turbidity development subsequently increases about four-fold, and then diminishes slightly. We may speculate that, in the presence of excess protein, all polyions... 

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