Interaction of recombinant human epidermal growth factor with phospholipid vesicles. A steady-state and time-resolved fluorescence study of the bis-tryptophan sequence (TRP49-TRP50) |
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Authors: | Ines M Li De La Sierra Michel Vincent Gabriel Padron Jacques Gallay |
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Institution: | (1) Centro de Ingeneria Genetica y Biotecnología, Apartado postal 6162 Habana, Cuba;(2) Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Centre National de la Recherche Scientifique, Ministère de l'Education Nationale et de la Jeunesse et des Sports, Commissariat à l'Energie Atomique, Université Paris Sud, Bâtiment 209D-91405 Orsay Cedex, France;(3) LURE, UPS Bât 209 D, 91405 Orsav Cedex, France |
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Abstract: | The interaction of recombinant human epidermal growth factor with small unilamellar phospholipid vesicles was studied by steady-state and time-resolved fluorescence of the bis-tryptophan sequence (Trp49-Trp50). Steady-state anisotropy measurements demonstrate that strong binding occurred with small unilamellar vesicles made up of acidic phospholipids at acidic pH only (pH 4.7). An apparent stoichiometry for 1,2-dimyristoyl-sn-phosphoglycerol of about 12 phospholipid molecules per molecule of human epidermal growth factor was estimated. The binding appears to be more efficient at temperatures above the gel to liquid-crystalline phase transition. The conformation and the environment of the Trp-Trp sequence are not greatly modified after binding, as judged from the invariance of the excited state lifetime distribution and from that of the fast processes affecting the anisotropy decay. This suggests that the Trp-Trp sequence is not embedded within the bilayer, in contrast to the situation in surfactant micelles (Mayo et al. 1987; Kohda and Inigaki 1992).Abbreviations DMPG
1,2-dimyristoyl-sn-phosphoglycerol
- hEGF
human Epidermal Growth Factor
- HPLC
high performance liquid chromatography
- MEM
Maximum Entropy Method
- POPC
1-palmitoyl, 2-oleoyl-sn-phosphocholine
- POPS
1-palmitoyl, 2-oleoyl-sn-phosphoserine
- SUV
small unilamellar vesicles
- Trp
tryptophan
- Trp-Trp
bis-tryptophan |
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Keywords: | Human recombinant epidermal growth factor Lipid-protein interactions Time-resolved fluorescence Bis-tryptophan |
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