Poly-guanidinium

An extended family of poly-guanidinium lipids was obtained by exploiting a combinatorial chemistiy approach (Figure 15.21). In application of the concept of libraries from libraries , a second generation library of mono-functionalized (polyguanidinium)-amines was synthesized and introduced into cationic lipids (Byk et al., 1998b). 

Figure 15.21 Synthesis of geometrically varied mono-functionalized poly (amino)-guanidine building blocks ( Libraires trom libraries ) tor the synthesis of geometrically varied lipo-poly-guanidinium-amines.

Byk, G., Soto, J., Mattler, C., Frederic, M. and Scherman, D. (1998b) Novel non-viral vectors for gene delivery Synthesis of a second generation library of mono-functionalized poly-(guanidinium)amines. Biotech. Bioeng., 61, 81-87. 

The contribution of the poly(Pro)II conformation to the ensemble of unordered peptides has been considered.1158 The temperature dependence of [0]222 for the peptide Ac-YEAAAKEAPAKEAAAKA-NH2 in 8 M guanidinium chloride and of poly(Lys) in water and in ethylene glycol/water (2 1) mixtures 156 was fitted to a two-state equation for a poly(Pro)II-unordered equilibrium with a temperature-independent AH and temperature-independent molar ellipticities for the two components. The peptide with a Pro at the central position is an unordered peptide, the spectrum of which has pronounced poly(Pro)II-like features at low temperatures. This fit yielded [0]222=- -9580 deg-cm2dmol 1 for the poly (Pro)II component and —5560 deg-cm2-dmol 1 for the unordered component. These values provide a method for roughly estimating the poly(Pro)II content, /Pn, of an unordered peptide from [0]222 ... 

Guanidinium (4) is protonated across a wider pH range than poly ammonium systems and consequently avoids many of their pH limitations. It is extensively... 

A few years earlier, in 1991, Williams et al. [22] had performed the structural analysis of poly(tetramethyl-p-silphenylene siloxane)-poly(di-methylsiloxane) copolymers (TMPS-DMS copolymers) by Si NMR. These copolymers were obtained by the condensation of bis-hydroxy(tetramethyl-p-silphenylene siloxane) 1 with a, tw-dihydroxy polydimethyl oligosiloxanes, in the presence of a guanidinium catalyst (cf. Scheme 8) ... 

Wang J, Li S, Zhang S. Novel hydroxideconducting polyelectrolyte composed of an poly(arylene ether sulfone) containing pendant quaternary guanidinium groups for alkaline fuel cell applications. Macromolecules 2010 43(8) 3890-6. 

Fig. lA-D. Immunofractionation of chromatin digested by micrococcal nuclease for various extents of time on an anti-poly(ADP-ribose) Sepharose column. HeLa nuclei from 10 cells were digested with micrococcal nuclease [50 units/10 nuclei at 37°C for 1 min (A), 5 min (B), 10 min (C), and 20 min (D)]. Soluble chromatin was subsequently prepared and immunofractionated on an anti-poly(ADP-ribose) Sepharose column. The columns were loaded and washed with phosphate buffered saline. Transmittance at 254 nm was continuously monitored. When no further UV-absorbing material was eluted, 6 M guanidinium hydrochloride was added to elute-bound material. The insets in each panel represent 1/50 of the DNA extracted from the pooled unbound U) and bound (B) peak fractions subjected to electrophoresis on 1.5% agarose. The gel was stained with ethidium bromide. (Taken from [10])... 

On the contrary, it is observed that with some proteins, the viscosity actually decreases when they are treated with 6 M guanidinium chloride. In such cases, one assumption is that the protein may be fibrous in nature and that denaturation has given it more flexibility as a random eoil. An example of such a case is afforded by poly(Y-benzyl-L-glutamate). The viscosity of this polypeptide solution actually decreases upon denaturation meaning that this polypepUde exists as a rigid rod in its native eondition and the random coil conformation upon denaturation is the more flexible form. The same is true about the protein collagen also. 

Fig.1 Synthesis of polymeric guanidinium salts through chemical modification of poly (acrylonitrile) resin...

Diaminobutane poly(propylene imine) dendrimers (DAB) were studied by Paleos et al. as a drug delivery system [20]. A dendrimer of the 5th generation with 64 amino end-groups (DAB-64) was decorated with PEG chains and guanidinium moieties (Scheme 8) in order to induce protective and targeting properties, respectively. The release of encapsulated molecules, such as pyrene, was triggered by titration with hydrochloric acid followed by the... 

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