2- Amino-4 -imidazole

Fig. 3.15 Model for allosteric inhibition of a protein-DNA complex by a polyamide-inter-calator conjugate. (Top) The GCN4 homodimer (yellow) is displaced by the intercalating moiety (green) of the polyamide conjugate. Blue and red spheres represent pyrrole and imidazole amino acids, respectively. The blue diamond represents / -alanine. (Bottom, left) Hydrogen-bonding model of an eight-ring hairpin polyamide-intercalator conjugate...

WvRTZ, N.R., J.M. Turner, E.E. Baird, and P. B. Dervan. Fmoc solid phase synthesis of polyamides containing pyrrole and imidazole amino acids. Org. Lett. 2001, 3, 1201-1203. 

The ionization state of the substrate can affect BBB transport of carrier-mediated substrates. For example, histidine is an imidazole amino acid that is highly charged under acidic conditions and crosses the BBB via the basic amino acid carrier. However, under neutral conditions, histidine is 90% neutral and traverses the BBB via the neutral amino acid carrier. 

Novel 2 -modified nucleoside triphosphate derivatives incorporating imidazole, amino or carboxylate pendant groups attached to the 5-position of pyrimidine base through alkynyl and alkyl spacers (115) have been synthesised. In one reported procedure, the appropriately protected modified nucleoside was phosphorylated with POCI3 in triethylphosphate in the presence of 1,8-bis(dimethylamino)naphthalene. The phosphorochloridate intermediate was then condensed in situ with tri-n-butylammonium pyrophosphate to yield the protected triphosphate analogue that was then deprotected. In another... 

New polyamides based on homo- and/or hetero-pyrrole and imidazole amino acids have been designed for high-affinity recognition of the minor groove of DNA (Fig. 7.12). 

Trifluoromethylphenyl)sulfonylethoxy-carbonyl group (Tsc), 2-(4-trifluoromethyl-phenylsulfonyl)ethoxycarbonyl, a base-labile protection group for amines, especially suited for the heteroaromatic pyrrole and imidazole amino acids Trp and His. The Tsc group differs from the 9-fiuorenylmethoxycarbonyl (Fmoc) group in decreased sensitivity toward premature cleavage [J. S. Choi et al., Tetrahedron 2005, 61, 2493]. 

Some poly(alkylene phosphate)s were modified by introducing derivatives of imidazole,amino acids,and/or NA bases as side groups. 

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