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Label-free measurements of the diffusivity of molecules in lipid membranes

Johansson, Björn ; Höök, Fredrik LU ; Klenerman, David and Jönsson, Peter LU (2014) In ChemPhysChem 15(3). p.91-486
Abstract

An important and characteristic property of a cell membrane is the lateral mobility of protein molecules in the lipid bilayer. This has conventionally been measured by labeling the molecules with fluorescent markers and monitoring their mobility by different fluorescence-based techniques. However, adding the label to the studied molecule may affect the system, so it is an assumption in almost all experiments that the measured mobility of the biomolecule with its label is the same as that of the unlabeled molecule. However, this assumption is rarely tested due to a lack of suitable methods. In this work, a new technique to perform label-free diffusivity measurements is developed and used to measure the effect of the label for two common... (More)

An important and characteristic property of a cell membrane is the lateral mobility of protein molecules in the lipid bilayer. This has conventionally been measured by labeling the molecules with fluorescent markers and monitoring their mobility by different fluorescence-based techniques. However, adding the label to the studied molecule may affect the system, so it is an assumption in almost all experiments that the measured mobility of the biomolecule with its label is the same as that of the unlabeled molecule. However, this assumption is rarely tested due to a lack of suitable methods. In this work, a new technique to perform label-free diffusivity measurements is developed and used to measure the effect of the label for two common protein-lipid systems: 1) streptavidin (SA) coupled to a supported lipid bilayer (SLB) through biotinylated lipids and 2) the extracellular part of the T-cell adhesion protein CD2, coupled to an SLB through histidine tags to nickel-chelating lipids. A measurable (≈12%) decrease in diffusivity is found for both labeled proteins, even though the molecular mass of the label is almost 100 times smaller than those of the proteins (≈50 kDa). The results illustrate the importance of being able to study different biophysical properties of cell membranes and their mimics without relying on fluorescent labels, especially if fluorescent labeling is difficult or is expected to affect the nature of the intermolecular interactions being studied.

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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
CD2 Antigens, Chelating Agents, Diffusion, Hydrodynamics, Lipid Bilayers, Nickel, Streptavidin, Journal Article, Research Support, Non-U.S. Gov't
in
ChemPhysChem
volume
15
issue
3
pages
6 pages
publisher
John Wiley & Sons
external identifiers
  • pmid:24402971
  • scopus:84894263360
ISSN
1439-7641
DOI
10.1002/cphc.201301136
language
English
LU publication?
no
id
0a56bb8c-0d3a-455f-995f-073665c74f16
date added to LUP
2018-01-26 10:26:23
date last changed
2020-01-13 00:25:28
@article{0a56bb8c-0d3a-455f-995f-073665c74f16,
  abstract     = {<p>An important and characteristic property of a cell membrane is the lateral mobility of protein molecules in the lipid bilayer. This has conventionally been measured by labeling the molecules with fluorescent markers and monitoring their mobility by different fluorescence-based techniques. However, adding the label to the studied molecule may affect the system, so it is an assumption in almost all experiments that the measured mobility of the biomolecule with its label is the same as that of the unlabeled molecule. However, this assumption is rarely tested due to a lack of suitable methods. In this work, a new technique to perform label-free diffusivity measurements is developed and used to measure the effect of the label for two common protein-lipid systems: 1) streptavidin (SA) coupled to a supported lipid bilayer (SLB) through biotinylated lipids and 2) the extracellular part of the T-cell adhesion protein CD2, coupled to an SLB through histidine tags to nickel-chelating lipids. A measurable (≈12%) decrease in diffusivity is found for both labeled proteins, even though the molecular mass of the label is almost 100 times smaller than those of the proteins (≈50 kDa). The results illustrate the importance of being able to study different biophysical properties of cell membranes and their mimics without relying on fluorescent labels, especially if fluorescent labeling is difficult or is expected to affect the nature of the intermolecular interactions being studied.</p>},
  author       = {Johansson, Björn and Höök, Fredrik and Klenerman, David and Jönsson, Peter},
  issn         = {1439-7641},
  language     = {eng},
  month        = {02},
  number       = {3},
  pages        = {91--486},
  publisher    = {John Wiley & Sons},
  series       = {ChemPhysChem},
  title        = {Label-free measurements of the diffusivity of molecules in lipid membranes},
  url          = {http://dx.doi.org/10.1002/cphc.201301136},
  doi          = {10.1002/cphc.201301136},
  volume       = {15},
  year         = {2014},
}