Nanometer to millimeter scale peptide-porphyrin materials

Daniil V. Zaytsev, Fei Xie, Madhumita Mukherjee, Alexey Bludin, Borries Demeler, Robert M. Breece, David L. Tierney, Michael Y. Ogawa

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


AQ-Pal14 is a 30-residue polypeptide that was designed to form an α-helical coiled coil that contains a metal-binding 4-pyridylalanine residue on its solvent-exposed surface. However, characterization of this peptide shows that it exists as a three-stranded coiled coil, not a two-stranded one as predicted from its design. Reaction with cobalt(III) protoporphyrin IX (Co-PPIX) produces a six-coordinate Co-PPIX(AQ-Pal14)2 species that creates two coiled-coil oligomerization domains coordinated to opposite faces of the porphyrin ring. It is found that this species undergoes a buffer-dependent self-assembly process: nanometer-scale globular materials were formed when these components were reacted in unbuffered H2O, while millimeter-scale, rod-like materials were prepared when the reaction was performed in phosphate buffer (20 mM, pH 7). It is suggested that assembly of the globular material is dictated by the conformational properties of the coiled-coil forming AQ-Pal14 peptide, whereas that of the rod-like material involves interactions between Co-PPIX and phosphate ion.

Original languageEnglish
Pages (from-to)2602-2609
Number of pages8
Issue number10
StatePublished - Oct 11 2010


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