Polycationic compounds

Polycationic compounds. Provided that no covalent bonds occur between the anionic atoms, b(XX)=0, equation (13.5) becomes ... 

The number of known polycationic compounds of main group elements is far less than that of polyanionic compounds. Examples include the chalcogen cations S]+, S]+, Se]o and Teg that are obtained when the elements react with Lewis acids under oxidizing conditions. The ions S]1, Sc]1 and Te] have a square structure that can be assumed to have a 6n electron system. 

Formation of a complex between DNA and polycationic compounds appears to be the initial and quite possibly a critical parameter for nonviral gene delivery. Several synthetic vector systems, which are generally cationic in nature, including poly(lysines), cationic liposomes or various types of block copolymers and recently dendrimers, have been shown to self-assemble with plasmid DNA [13-15] [16]. Specific physicochemical properties manifested by these DNA complexes depend on the type of cationic agent used however, interesting patterns for such interactions are beginning to evolve [17, 18]. Under certain conditions, the interaction of DNA with polyvalent cations results in... 

The aminoglycosides are a closely related family of antibiotics produced almost exclusively by members of the genus Streptomyces and Micromonospora (Table 1.19). Most are polycationic compounds, composed of a cyclic amino alcohol to which amino sugars are attached. They all induce their bacteriocidal effect by inhibiting protein synthesis (apparently by binding to the 30 S and, to some extent, the 50 S, ribosomal subunits). Most are orally inactive, generally necessitating their parenteral administration. 

The number of known polycationic compounds of main group elements is far less than that of polyanionic compounds. Examples include the chalcogen cations S4 , S , Se" ... 

III. Nociceptive Behavior Induced by i.t.-Administered Prodynorphin-Derived Peptides and Polycationic Compounds... 

The experimental evidence has shown that the limiting conditions, that is CC = 0 for polyanionic compounds and AA = 0 for polycationic compounds, can be taken for granted. But note, that in general these equations can be applied only if all bonds ire two electron bonds and additional electrons remain inactively in the non-bonding orbitals of the cations or anions. Thus the compounds must be semiconductors. If the compounds are metallic, the applicability of these equations is not guaranteed. 

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