The Molecular Structure of Human Red Blood Cell Membranes from Highly Oriented, Solid Supported Multi-Lamellar Membranes

Abstract

We prepared highly oriented, multi-lamellar stacks of human red blood cell (RBC) membranes applied on silicon wafers. RBC ghosts were prepared by hemolysis and applied onto functionalized silicon chips and annealed into multi-lamellar RBC membranes. High resolution X-ray diffraction was used to determine the molecular structure of the stacked membranes. We present direct experimental evidence that these RBC membranes consist of nanometer sized domains of integral coiled-coil peptides, as well as liquid ordered (lo) and liquid disordered (ld) lipids. Lamellar spacings, membrane and hydration water layer thicknesses, areas per lipid tail and domain sizes were determined. The common drug aspirin was added to the RBC membranes and found to interact with RBC membranes and preferably partition in the head group region of the lo domain leading to a fluidification of the membranes, i.e., a thinning of the bilayers and an increase in lipid tail spacing. Our results further support current models of RBC membranes as patchy structures and provide unprecedented structural details of the molecular organization in the different domains.

Hybrid Erythrocyte Liposomes: Functionalized Red Blood Cell Membranes for Molecule Encapsulation

“…DMPC, POPC, and POPS show a gradual increase in lamellar spacing and head–head distance with an increasing fraction of RBC membranes, as shown in Figures 3b,c. It converges to ≈56 Å for the d z ‐spacing and ≈44 Å for the head‐head distance, in good agreement with previously published measurements on red‐blood cell membranes 21…”

“…The degree of order is quantified by fitting Herman's orientation function, as detailed in the Experimental Section. A degree of orientation between ≈82% and ≈97% was determined, in good agreement with previous studies on pure red blood cells,21 and on mono‐ or multicomponent synthetic membranes 22…”

“…The preparation is based on a protocol first published by Himbert et al21 All blood samples were collected using sodium heparin coated venous blood collection tubes from BD (Product Number: BD 367874). The blood was washed twice and the RBC were isolated as described in ref.…”

Binary Encoding of Random Peptide Sequences for Selective and Differential Antimicrobial Mechanisms

“…[25] Anionic and zwitterionic unilamellar vesicles,A UVs and ZUVs,r espectively,p rovided microbial and mammalian membrane mimetics, [25,26] while weakly anionic AUVs (wAUVs) emulated erythrocytal membranes [27] (see the Supporting Information). [25] Anionic and zwitterionic unilamellar vesicles,A UVs and ZUVs,r espectively,p rovided microbial and mammalian membrane mimetics, [25,26] while weakly anionic AUVs (wAUVs) emulated erythrocytal membranes [27] (see the Supporting Information).…”

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“…The presence of this framework forms conditions for self-organization (self assembly) of biological tissues, which occurs without human interference, being supported by weak non-covalent (hydrogen, ion) bonds upon hydrophobic interaction of tissues. A similar organization of biological macro molecules in nature occurs, for example, in phospholipids, which are the main components of plasma cellular membranes 9 .…”