Background: Vitamin E is comprised of α, β, γ and δ-tocopherols (Ts) and α, β, γ and δ-tocotrienols (T3s). Vitamin E has neuroprotective antioxidant, anti-cancer, and cholesterol lowering effects. Intracellular trafficking of these isomers remains largely unknown, except for αT which is selectively transported by αT transfer protein (αTTP).
Objective: This study aimed to determine binding of vitamin E isomers on transport proteins using in silico docking.
Method: Transport proteins were selected using AmiGo Gene Ontology tool based on same molecular function annotation as αTTP. Protein structures were obtained from Protein Data Bank. Ligands structures were obtained from ZINC database. In silico docking was performed using SwissDock.
Results: A total of 6 transport proteins were found: SEC14-like protein 2, glycolipid transfer protein (GLTP), pleckstrin homology domain-containing family A member 8, collagen type IV alpha-3-binding protein, ceramide-1-phosphate transfer protein and afamin. Compared with other transport proteins, αTTP had the highest affinities for all isomers except βT3. Binding order of vitamin E isomers toward αTTP was γT > βT > αT > δT > αT3 > γT3 > δT3 > βT3. GLTP had higher affinity for tocotrienols than tocopherols. βT3 bound stronger to GLTP than αTTP.