Pyrrole-imidazole tetramer

Figure 7.12. Molecular structure of a hairpin pyrrole-imidazole tetramer.

Among the more complex structures, carteramine A and stylissadines A and B are respectively dimers (C22N10) and tetramers (C44N20) of C11N5 pyrrole-imidazole alkaloids. Isolated from the species Stylissa carteri harvested in Japan, carteramine A is an inhibitor of neutrophil chemotaxis (IC50 5 pM), and may lead to a new generation of anti-... 

The dipeptides Gly-L-His, L-Ala-L-His, and L-Ala-D-His initially form 3N complexes with palladium(II), bonding through the amino, deprotonated peptide, and imidazole nitrogens. When the pH is raised above 9.5, the pyrrole proton is ionized, resulting in a 4N tetramer formation." ... 

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