Conformational adaptation of annexin V upon binding to liposomes: a time-resolved fluorescence study.
The fluorescence intensity decay of the single tryptophan residue, Trp-187, of free annexin V is described by the sum of three lifetime components (5.4, 1.3, and 0.4 ns), which may be correlated to three ground-state classes of Trp conformers. The two major classes (44 and 48%) are embedded in the protein matrix. When annexin V binds to calcium and liposomes made of dioleoylphosphatidylcholine and dioleoylphosphatidylserine, similar results are obtained whatever the (10-200) lipid ratio. The Trp fluorescence decay is fitted with only two components (6.9-7.2 and 2.0-2.2 ns). Decay-associated spectra reveal that the longest lifetime of bound annexin V can be related to Trp residues (60%) located in a partially polar environment, which could correspond to the protein-membrane interface. The shortest lifetime is attributed to Trp residues (40%) which reside in a hydrophobic surrounding: these Trp residues would penetrate into the phospholipid membrane and contribute to the stabilization of the 2D-array of annexin V molecules.
Follenius-Wund
A
A
Laboratoire de Biophysique, Faculté de Pharmacie, URA CNRS 491, Université Louis Pasteur de Strasbourg, Illkirch, France. anny.wund@pharma.u-strasbg.fr
Piémont
E
E
Freyssinet
J M
JM
Gérard
D
D
Pigault
C
C
D017304:Annexin A5 / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D006801:Humans; D008081:Liposomes / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D010920:Placenta / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D014364:Tryptophan
D017304:Annexin A5; D008081:Liposomes; D010713:Phosphatidylcholines; D014364:Tryptophan; C017251:1,2-oleoylphosphatidylcholine; D002118:Calcium