Binding of a fluorescent lipid amphiphile to albumin and its transfer to lipid bilayer membranes.
Biophys J
; 84(1): 386-99, 2003 Jan.
Article
in En
| MEDLINE
| ID: mdl-12524292
ABSTRACT
Kinetics and thermodynamics of the binding of a fluorescent lipid amphiphile, Rhodamine Green(TM)-tetradecylamide (RG-C(140)), to bovine serum albumin were characterized in an equilibrium titration and by stopped-flow fluorimetry. The binding equilibrium of RG-C(140) to albumin was then used to reduce its concentration in the aqueous phase to a value below its critical micelle concentration. Under these conditions, the only two species of RG-C(140) in the system were the monomer in aqueous solution in equilibrium with the protein-bound species. After previous determination of the kinetic and thermodynamic parameters for association of RG-C(140) with albumin, the kinetics of insertion of the amphiphile into and desorption off lipid bilayer membranes in different phases (solid, liquid-ordered, and liquid-disordered phases, presented as large unilamellar vesicles) were studied by stopped-flow fluorimetry at 30 degrees C. Insertion and desorption rate constants for association of the RG-C(140) monomer with the lipid bilayers were used to obtain lipid/water equilibrium partition coefficients for this fluorescent amphiphile. The direct measurement of these partition coefficients is shown to provide a new method for the indirect determination of the equilibrium partition coefficient of similar molecules between two defined lipid phases if they coexist in the same membrane.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Rhodamines
/
Serum Albumin, Bovine
/
Lipid Bilayers
Limits:
Animals
Language:
En
Journal:
Biophys J
Year:
2003
Type:
Article
Affiliation country:
Portugal