en.wikipedia.org/wiki/Attenuated_total_reflectance
1 correction found
Water-soluble proteins to be investigated require Polyhistidine-tags, allowing the macromolecule to be anchored to a lipid bilayer, which is attached to a Germanium crystal or other suitable optical media.
Polyhistidine tags are not a general requirement for ATR-FTIR studies of soluble protein/drug interactions. Published ATR-FTIR assays immobilize target proteins in other ways, including antibody capture on germanium surfaces.
Full reasoning
The word "require" makes this claim too strong and factually incorrect. ATR-FTIR studies of soluble protein–ligand or protein–drug interactions do not universally require polyhistidine tags or anchoring through a lipid bilayer.
A direct counterexample is a published ATR-FTIR drug-intervention assay for human tau and amyloid-β, both soluble protein targets in the study setup. The authors state that they developed an ATR-FTIR sensor that "uses surface bound antibodies to immobilize a desired target protein" and further explain that they used silane chemistry to covalently attach monoclonal antibodies to the germanium ATR crystal. That contradicts the article’s claim that soluble proteins require polyhistidine tags.
A second ATR-FTIR drug-discovery paper on HSP90 describes a recently established method to immobilize his-tagged and lipidated proteins on germanium internal reflection elements, presenting his-tag capture as one method the authors established—not as a universal requirement for all soluble proteins. Together, these sources show that polyhistidine tagging is optional and application-dependent, not mandatory.
2 sources
- An ATR-FTIR Sensor Unraveling the Drug Intervention of Methylene Blue, Congo Red, and Berberine on Human Tau and Aβ - PMC
We developed an attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) sensor, which uses surface bound antibodies to immobilize a desired target protein... we employed silane chemistry to modify the surface of the germanium ATR crystal to covalently attach the desired monoclonal IgG antibody.
- Ligand-Induced Conformational Changes in HSP90 Monitored Time Resolved and Label Free-Towards a Conformational Activity Screening for Drug Discovery - PMC
Recently, we established a robust method to specifically immobilize his-tagged and lipidated proteins on germanium IREs... This recent breakthrough allowed us to use ATR-FTIR spectroscopy as a flow-through-based sensor of conformational change.