Conjugation of cytochrome c with hydrogen titanate nanotubes: Novel conformational state with implications for apoptosis

摘要

We show that hydrogen titanate (H_2Ti_3O_7) nanotubes form strongly associated reversible nano-bio-conjugates with the vital respiratory protein, cytochromec. Resonance Raman spectroscopy along with direct electrochemical studies indicate that in this nano-bio-conjugate, cytochromec exists in an equilibrium of two conformational states with distinctly different formal redox potentials and coordination geometries of the heme center. The nanotube-conjugated cytochromec also showed enhanced peroxidase activity similar to the membrane-bound protein that is believed to be an apoptosis initiator. This suggests that such a nanotube-cytochromec conjugate may be a good candidate for cancer therapy applications.