To characterize a transmembrane protein by High Resolution Imaging and localize its binding sites, BioMeca® provides 2 solutions :
- Force-Distance curve-based Atomic Force Microscopy (FD-based AFM) technology for High Resolution Imaging,
- AFM tips functionalization with a tris-Ni+-NTA groups, to detect the specific protein binding sites, at the nanometer resolution.
These technologies allow BioMeca® to quantify the blinding strength of tris-Ni+-NTA groups to histidine residues and validate the number of TransMembrane Domains (TMD).
A : Mapping adhesion forces on membrane proteins using FD-based AFM. When recording an AFM topograph an approach (blue) and retraction (yellow) cycle between AFM tip and biological sample is performed for every pixel of the image. In each cycle, the cantilever deflection and the distance travelled by the AFM tip is monitored and transformed into an approach and retraction Force Distance (FD) curve
B : Functionalization of AFM tip (tris-Ni2+-NTA)
High resolution AFM image of two proteoliposomes immobilized on a mica surface. 1: proteoliposome 1, 2 : proteoliposome 2.
Characterization of membrane proteins embedded in the lipid bilayer of liposomes is not easy to investigate. As shown in this study, AFM approach provides, with one single instrument, information about the protein density, the protein orientation and the protein folding in the lipid bilayer of a complex material as liposomes.
In addition, AFM technology does not require the labelling of the proteins which renders this approach quite straightforward to use a Quality Control test. AFM might thus have a potential to become a standard method to control protein quality in the bioproduction processes.
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