Poly-L-arginine

Ohtake K, Maeno T, Ueda H, Ogihara M, Natsume H, Morimoto Y (2003) Poly-L-arginine enhances paracellular permeability via serine/threonine phosphorylation of ZO-1 and tyrosine dephosphorylation of occludin in rabbit nasal epithelium. Pharm Res 20 1838-1845. 

Under a variety of conditions, plasmid DNA undergoes a dramatic compaction in the presence of condensing agents such as multivalent cations and cationic polymers. Naked DNA coils, typically with a hydrodynamic size of hundreds of nanometers, after condensation it may become only tens of nanometer in size. Contrary to proteins which show a unique tertiary structure, DNA coils do not condense into unique compact structure. Cationic polymers execute their gene carrier function by their condensation effect on gene materials and, furthermore, their protection effect on DNA from nuclease digestion. Currently, the most widely used cationic polymers in research include linear or branched PEI (poly (ethyleneimine) (161-165), polypeptides such as PLL (poly-L-lysine) (166-169), PLA (poly-L-arginine) (170). 

Blackwell and his co-workers have used circular dichroism spectroscopy to study the interactions of glycosaminoglycans with collagen, and with synthetic cationic polypeptides. In the absence of glycosaminoglycans, poly-L-lysine and poly-L-arginine exist in an extended charged coil conformation. Glycosaminoglycans bind to these cationic polypeptides and cause them to assume an a-helical conformation. In a series of systematic studies (76-83). Blackwell and his co-workers... 

The work presented in the next section concerns the immobilization of retinoic acid by three polyamino acids poly(-L-lysine), poly(-L-arginine) and poly(-L-histidine). The mesomorphous structure of these complexes, which are prepared as nano-particles, has been examined. Then we will report on the physicochemical characteristics of water-soluble complexes formed between PEO-PLL block copolymers and retinoic acid. The structure in the solid-state and solution are discussed. Further the dissociation of the complex when changing the pH is reported. Finally, the immobilization of retinoic acid by PEI with different molecular weights is presented. 

Fig. 12 Substances used for complex formation and nanoparticles, (retinoic acid) All-trans retinoic acid, (PLA) poly(-L-arginine), (PLH) poly(-L-histidine), (PLL) poly(-L-ly-sine). As dispersing agent a tri-block copolymer was used. It consisted of ethylene oxide and propylene oxide (Poloxamer 188). Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

Fig. 14 Wide-angle X-ray diagrams of crystalline all-trans retinoic acid (curve a) and its complexes with polyamino acids. In the curve of poly(L-arginine) retinoate and poly(L-lysine) retinoate (curves b and d, respectively) no crystalline reflections were found. However, three weak crystalline reflections are present in the curve of poly(L-histidine) retinoate at s=1.69, 2.48 and 2.73 nm-1 (curve c). This is indicative of a partially crystalline complex structure. Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

In conclusion it was shown that the solid-state complexes formed by poly(L-arginine), poly(L-histidine) and poly(L-lysine) cations and retinoic acid can be prepared as films and nano-particles. The high content of retino-ate moieties, the absence of crystallinity and low particle sizes could make these complexes interesting as a new carrier for the delivery of retinoic acid, either transdermal or in body fluids. It may be speculated that supramolecu-lar structures such as the smectic A-like nano-particles of the tart-type pre-... 

Westergren I, Johansson BB (1993) Altering the blood-brain barrier in the rat by intracarotid infusion of polycations A comparison between protamine, poly-L-lysine and poly-L-arginine. Acta Physiol Scand 149 99-104. 

Chitosan, poly-L-arginine chitosan, aminated gelatin... 

Other cationic polymers, such as poly-L-arginine and aminated gelatin, were found to have promising enhancing effects on nasal peptide absorption. 

Ohtake, K. Natsume, H. Ueda, H. Morimoto, Y. Analysis of transient and reversible effects of poly-L-arginine on the in vivo nasal absorption of FITC-dextran in rats. J. Control. Release 2002, 82 (2-3), 263-275. 

Ohtake, K. Maeno, T. Ueda, H. Natsume, H. Morimoto, Y. Poly-L-arginine predominantly increases the paracellular permeability of hydrophilic macromolecules across rabbit nasal epithelium in vitro. Pharm. Res. 2003,20 (2), 153-160. 

Poly(L-arginine)6o-Wocfc-poly(L-leucine)2o (PLArg-/ -PLLeu, Fig. lOg) showed similar physical properties as PLLys60-fe-PLLeu2o and also formed micrometersized vesicles in aqueous solution. These vesicles were able to entrap water-soluble species, such as dextran, and could be extruded through polycarbonate filters to yield stable, low-polydispersity vesicles of controllable diameter down to 50 nm [53]. 

Figure 1. Circular dichroism spectra at 24-25° C for cationic poly(L-arginine) and a nonionic random copolypeptide of hydroxypropyl-L-glutamine (83%) and hydroxyamyl-L-glutamine (17%). (Al) Poly(L-arginine) in water, (A2) poly(L-arginine) in 0.0001 M sodium doecyl sulfate, (HG1) hydroxyalkylglutamine copolypeptide in water, and (HG2) hydroxyalkylglutamine copolypeptide in 0.003 M sodium dodecyl sulfate. Spectra for poly(L-arginine) are from reference 12, and spectra for the random copolypeptide are from reference 15.

To date, aluminum salts, MF59, and virosomes are the only adjuvants which have been used in licensed products, though many more adjuvants (e.g., poly-L-arginine, CpG-ODN) have been tested in pre-clinical experiments and/or in clinical... 

Further studies using either peptides (Fig. 3.1) or whole proteins (Fig. 3.2) showed that, in the presence of poly-L-arginine the enhanced uptake of antigens by MHC class Il-positive APCs takes also place in vivo (compare Fig. 3.1 A versus Fig. 3.1 B, where peptide was injected alone). It could be also... 

Fig. 3.1 Poly-L-arginine enhances the uptake of antigens by MHC class ll-positive antigen-presenting cells in vivo. A peptide derived from listerioly-sin from Listeria monocytogenes was labeled with SFX (fluorescein, green fluorescent dye) and injected in combination with poly-L-arginine (A) or...

Fig. 3.3 Poly-L-arginine induces the formation of a depot at the injection site. Melanoma-derived peptide TRP-2igi igg la beled with SFX (fluorescein) was injected subcutaneously into the flank of...

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