a-TTP is the cytosolic carrier of vitamin E in hepatocytes. It retains selectively a-tocopherol out of the eight existing isoforms.
Our free energy perturbation calculations explain the selectivity of a-TTP for a-tocopherol in terms of a combination of optimal van der Waals contacts and conformational energy of the flexible binding pocket of the protein. Specific mutants able to modulate the selectivity towards different tocopherols were also characterized.

This work was carried out by Rachel Helbling in the group of Prof. Michele Cascella.

References:

• R. Helbling, W. Aeschimann, F. Simona, A. Stocker, M. Cascella;
  "Engineering Tocopherol Selectivity in a-TTP: A Combined In Vitro/In Silico Study"
  PLoS ONE, 7, e49195/1-11, (2012); doi:10.1371/journal.pone.0049195.