Nanopore Analysis of the Folding of Zinc Fingers

A simple model for conformational studies of protein folding involving the interaction of metal ions with Zn-finger peptides, investigated by nanopore analysis, was demonstrated. Scatter plots of blockade time against current for Zif268 with increasing concentrations of Zn(II) shows that the blockade times having values of 0.07 and 0.30 ms. The results also show that a single folded conformation upon bumping gives a single blockade current compared to the more variable blockade currents or partially folded molecules. The rate of diffusion to the pore is different for folded and unfolded molecules, altering their effective concentrations. The free energy of Zn(II) binding to a Zn is about -16 Kcal mol-1, which is similar to the free energy of folding. It is also seen that the Zn-filger motif is more tightly-folded and cannot thread through the pore as it unfolds.