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16507.0 [No comment] 20.09.2010 14:16 Released

ID: 16507.0, MPI für biophysikalische Chemie / Spektroskopie und photochemische Kinetik (Prof. Jürgen Troe)
Interaction of human serum albumin with membranes containing polymer-grafted lipids: spin-label ESR studies in the mushroom and brush regimes
Authors:Bartucci, R.; Pantusa, M.; Marsh, D.; Sportelli, L.
Date of Publication (YYYY-MM-DD):2002-08-19
Title of Journal:Biochimica et Biophysica Acta-Biomembranes
Issue / Number:1
Start Page:237
End Page:242
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:The adsorption of human serum albumin (HSA) to dipalmitoyl phosphatidylcholine (DPPC) bilayer membranes containing poly(ethylene glycol)-grafted dipalmitoyl phosphatidylethanolamine (PEG-DPPE) was studied as a function of content and headgroup size of the polymer lipid. In the absence of protein, conversion from the low-density mushroom regime to the high-density brush regime of polymer-lipid content is detected by the change in ESR outer hyperfine splitting, 2A(max), of chain spin-labelled phosphatidylcholine in gel-phase membranes. The values of 2A,; remain constant in the mushroom regime, but decrease on entering the brush regime. Conversion between the two regimes occurs at mole fractions X- PEG(m --> h) approximate to 0.04, 0.01-0.02 and 0.005-0.01 for PEG-DPPE with mean PEG molecular masses of 350, 2000 and 5000 Da, respectively, as expected theoretically. Adsorption of HSA to DPPC membranes is detected as a decrease of the spin label 2.4(max) hyperfine splitting in the gel phase. Saturation is obtained at a protein/lipid ratio of ca. 1:1 w/w. In the presence of polymer-grafted lipids, HSA adsorbs to DPPC membranes only in the mushroom regime, irrespective of polymer length. In the brush regime, the spin-label values of 2A(max) are unchanged in the presence of protein. Even in the mushroom regime, protein adsorption progressively becomes strongly attenuated as a result of the steric stabilization exerted by the polymer lipid. These results are in agreement with theoretical estimates of the lateral pressure exerted by the grafted polymer in the brush and mushroom regimes, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.
Free Keywords:polymer lipid; PEG-lipid; serum albumin; steric protection; opsonization; liposome; lipid-protein interaction; spin label; electron spin resonance
Comment of the Author/Creator:Date: 2002, AUG 19
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für biophysikalische Chemie/Abt. Jürgen Troe / 010
External Affiliations:Univ Calabria, Dipartimento Fis, Lab Biofis Mol, Cubo 31 C, I-; 87036 Arcavacata Di Rende, CS, Italy; Univ Calabria, Unita INFM, I-87036 Arcavacata Di Rende, CS, Italy