Poly ornithine

The use of plastic materials for routine cell culture on the laboratory scale was introduced at the end of the 1960s, and some characteristics of glass surface, such as hydrophobicity and negative charge, were maintained in these materials. Polystyrene is the most widely used plastic material for animal cell adhesion at present, because of its surface characteristics, its low cost, and also its transparency. For more demanding cell lines, the surface has to be submitted to a treatment that involves coating with proteins such as poly-lysine, poly-ornithine, or extracellular matrix-derived proteins such as fibronectin, laminin, and collagens. 

Polymers of poly(L-ornithine) possessing varying contents of azobenzene groups, from 20% up to almost 100% [Scheme 5, VIII (n= 3)], were found to be essentially a-helical in HFP when the samples were kept in the dark. The CD spectra also exhibited a couplet of bands centered at about 320 nm, attributed to electronic interactions between the azo side chains in the trans configuration. Irradiation at 360 nm and the consequent trans—xis photoisomerization, abolished the side chain CD... 

A sample of poly(L-ornithine) containing 48 mol% azo units was found to adopt the a-helix structure in HFP/water = 1/1. In this solvent mixture, however, irradiation at 360 nm followed by irradiation at 460 nm produced the trans-cis photoisomerization of the azo moieties, but did not induce any change of the backbone conformation. When the surfactant sodium dodecyl sulfate was added to the HFP/water solvent mixture, the CD spectrum displayed an intense side chain CD couplet and a negative band at about 225 nm which was assigned to the presence of a P-structure. The CD bands were almost completely abolished upon trans-cis photoisomerization. 

Neural stem cells are known for their sensitivity to the environment. Jan and Kotov reported the differentiation of mouse embryonic neural stem cells on SWNT-polyelectrolyte multilayer thin films [poly(ethylene imine) PEI/SWNT, six layers], which were assembled layer by layer.111 The cells were successfully differentiated to neurons, astrocytes, and oligodendrocytes with a clear formation of neurites. Compared to the widely used poly(L-ornithine) (PLO) substrates, the six-layer PEI/ SWNT thin films exhibited similar properties in terms of biocompatibihty, neurites outgrowth, and the expression of neural markers.111... 

Satake I, Yang JT. Interaction of sodium decyl sulfate with poly(L-ornithine) and poly(L-lysine) in aqueous solutions. Biopolymers 1976 15 2263-2275. 

Figure 21.10 depicts depicts synthesis of putrescine, spermidine, and spermine from ornithine.. The polyamines are polycationic substances that stabilize intracellular conformations of negatively charged nucleic acids. Poly amines bind to phosphates on both strands of a duplex nucleic acid, thereby stabilizing double-stranded DNA or a duplex region of RNA. 

The helix-coil transitions of poly(N-5-carbobenzoxy-L-ornithine) (PCBO) (Boccalon et al., 1972), poly(7-benzyl-L-glutamate) (PBLG) (Paolillo et al., 1972 Allerhand and Oldfield, 1973 Bradbury et al.,... 

The oxidation product has been isolated as its 2,4-dinitrophenylhydrazone and corresponds with -keto-6-aminovaleric acid. Putrescine, arginine, Manske s 1 (+) acetylornithine (118) and other related amino acids are oxidized much less readily if at all. The same authors have extracted an ornithine dehydrogenase from the young roots of Datura tatula. It requires the cooperation of a coenzyme not yet identified, and appears unable to oxidize putrescine and amino acids other than ornithine and to a lesser extent glutamic. Either of these systems, or the two linked into a H-transfer chain, would seem able to catalyze the oxidation of ornithine in the living tissues. No carbon dioxide was released from ornithine by the poly-phenolase system but on addition of an unwashed belladonna tissue-suspension carbon dioxide was liberated, presumably by decarboxylation of the a-keto-5-aminovaleric acid formed by the oxidation. 

Preclinical Results Obtained with Particles. Poly-L-lysine and poly-L-Ornithine were used to generate particles that can entrap pDNA. The cationic polymers can be coupled to a targeting molecule such as galactose or mannose for enhanced delivery to the liver after intravenous or intraportal injections in mice [102-104]. Expression in other organs than the liver (for example, kidneys) is observed however, expression in the liver using these particles is dominant. Such particles are found to be more efficient and to persist for a longer time in the circulation than liposomes. Hepatic expression of the pDNA delivered by poly-L-Lysine particles can be found several months after delivery [105]. These promising formulations were not evaluated in humans. 

Yamamoto H, Nishida A, Takimoto T, Nagai A. 1990. Photoresponsive peptide and polypeptide systems. VIII. Synthesis and reversible photochromism of azo aromatic poly(L ornithine). J Polym Sci, Part A Polym Chem 28(1) 67 74. 

---