Fluorescent tocopherols as probes of inter-vesicular transfer catalyzed by the alpha-tocopherol transfer protein.
Novel fluorescent analogues of alpha-tocopherol have been prepared that incorporate the useful fluorophores nitrobenoxadiazyl (NBD) and anthroyloxy (AO). Both fluorescent tocopherol analogues bind specifically to recombinant human tocopherol transfer protein (hTTP). The NBD-alpha-tocopherol is particularly useful for protein-binding assays, whereas the AO-alpha-tocopherol was designed to be one of a pair of chromophores for a fluorescence resonance energy transfer (FRET) assay of intervesicular tocopherol transfer. It is now possible to follow AO-alpha-tocopherol transfer from donor lipid vesicles composed of predominantly phosphatidylcholine (PC) to acceptor lipid vesicles containing PC and a quenching lipid NBD-PE (2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[7-nitro-2-1,3-benzoxadiazol-4-yl]). The presence of hTTP substantially increases the rate of AO-alpha-tocopherol transfer over the uncatalyzed spontaneous rate.
Atkinson
Jeffrey K
JK
Department of Chemistry and Centre for Biotechnology, Brock University, St. Catharines, Ontario, Canada. jatkin@brocku.ca
Nava
Phillip
P
Frahm
Grant
G
Curtis
Valerie
V
Manor
Danny
D
D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D006801:Humans; D008081:Liposomes / Q000378:metabolism*; D024505:Tocopherols / Q000378:metabolism*
D002352:Carrier Proteins; D005456:Fluorescent Dyes; D008081:Liposomes; C017763:alpha-tocopherol transfer protein; D024505:Tocopherols