Molecular assembly of Zn porphyrin complexes using synthetic light-harvesting model polypeptides.

Synthetic single alpha-helix hydrophobic polypeptides, which have similar amino acid sequences to the hydrophobic core in the native light-harvesting 1-beta polypeptide from Rhodobacter sphaeroides, formed Zn porphyrin complexes on a gold electrode, as well as in n-octyl-beta-glucoside micelles: this process is dependent on the structure of the pigments and the polypeptides. Interestingly, an enhanced photoelectric current was observed when Zn mesoporphyrin monomer complexed with the synthetic light-harvesting model polypeptide in an alpha-helical configuration was assembled with a defined orientation onto the electrode. Analog of these light-harvesting model complexes are also useful in providing insights into the effect of polypeptide structure on the formation of light-harvesting complexes on and off electrodes.