Spectral Shift and MST Services

Domainex offers world-leading services to measure interactions between ligands and biomolecules

Confirm direct target engagement, quantify binding affinities and prioritise binders with solution-phase assays designed to support fragment screening, hit validation, mechanism-of-action studies, lead optimisation and challenging drug discovery programmes.

Domainex provides Spectral Shift, microscale thermophoresis (MST) and temperature-related intensity chance (TRIC) assay services to measure direct interactions between ligands and biomolecules in solution. The biophysics team at Domainex has supported discovery programmes with these technologies for over 10 years and has been an early adopter of each new technique; we have identified, validated and prioritised binders across a wide range of target classes over this time.
 

Biophysical assay samples

Benefits of Domainex's Spectral Shift/MST Service

Key benefits of Domainex Spectral shift service - 1. No target immobilisation. 2. Hit confirmation and affinity determination. 3. Works across challenging targets. 4. Mechanism of action studies. 5. Expert data interpretation

Where Spectral shift, MST and TRIC add value

Spectral Shift, MST and TRIC are valuable when you need rapid evidence of direct binding to support decision-making in early drug discovery. These solution-phase assays can help confirm target engagement, rank compounds by affinity and investigate challenging biological systems where immobilisation-based approaches may not be ideal.

This service is especially useful for:

Hit Identification and Optimisation

  • Confirm direct binding of hits, fragments, tool compounds or biologics
  • Measure binding affinity from weak fragment interactions through to high-affinity ligands
  • Rank and prioritise compounds during hit identification, hit validation or lead optimisation
  • Screen fragment libraries or focused compound sets using a medium-throughput assay format

Challenging Targets and Mechanisms

  • Study protein complexes, RNA, membrane proteins, molecular glues and bifunctional ligands
  • Avoid potential artefacts from immobilisation where binding sites may be blocked or target behaviour altered
  • Perform competition or probe-displacement studies to explore binding sites, mechanisms or compound selectivity
  • Generate orthogonal biophysical evidence alongside techniques such as GCI (or SPR), DSF or ITC

This makes the service especially useful for programmes where fast, reliable binding data are needed to guide which compounds, fragments or biological interactions should move forward.

Spectral Shift data for a) ternary complex formation and molecular glue characterisation, b) antagonist binding to adenosine A2a receptor in a polymer nanodisc and c) preQ1binding to preQ1 Riboswitch

Figure 1. Spectral Shift data for a) ternary complex formation and molecular glue characterisation, b) antagonist binding to adenosine A2a receptor in a polymer nanodisc and c) preQ1binding to preQ1 Riboswitch

Capabilities at Domainex

TechnologyHow it is used at DomainexApplications

Spectral Shift

Recommended starting point for most projectsHit confirmation, fragment screening, affinity ranking, challenging targets and medium-throughput workflows (up to 3,000 samples/day)

TRIC

Complementary readout on the Dianthus platform where technically usefulSystems where ligand binding produces a temperature-related change in fluorescence intensity, for example by altering the fluorophore environment or inducing conformational change

MST

Established method retained for relevant cases and client familiarityProjects where an MST-based approach is specifically requested or technically justified

Spectral Shift: Our Preferred Platform for Most Targets

Spectral Shift is the solution-phase binding technology we most commonly recommend for client projects, as it provides a robust, sensitive and medium-throughput (384-well) approach that works well across a broad range of target classes. The method monitors ligand-induced changes in the emission profile of a fluorescently labelled target, allowing direct binding to be measured without immobilising the biomolecule.

By starting with Spectral Shift, clients can often generate robust binding data faster and with lower sample consumption than with more traditional solution-phase methods. This makes it particularly useful for early-stage programmes where targets, ligands or assay conditions are still being optimised.

A graph of wavelength vs Fluorescence intensity for spectral shift

Figure 2. Shifts in the fluorophore’s emission profile, caused by ligand binding under isothermal conditions, measured by Spectral Shift.

Impact of ligand interactions on chemical environment of fluorophore

Figure 3. The impact of ligand interactions on the chemical environment of the fluorophore

In our experience, Spectral Shift often provides a stronger and more reliable assay window than traditional MST or TRIC readouts, particularly for challenging targets or screening applications where sensitivity, throughput and sample efficiency are important.

TRIC: A Complementary Readout for Selected Systems

Temperature-Related Intensity Change (TRIC) can be measured on the Dianthus platform alongside Spectral Shift and may provide useful complementary information in selected systems. It monitors changes in fluorescence intensity caused by temperature-related effects around the labelled biomolecule, which can be influenced by ligand binding or ligand-induced conformational changes.

Principle of TRIC fluorescence intensity changing with increasing temperature, which is affected by ligand binding

Figure 3. Principle of TRIC: fluorescence intensity changing with increasing temperature, which is affected by ligand binding

effect of ligand binding TRIC graphs

Figure 4: a) Representation of the effect of ligand binding on the TRIC signal. In this example, when ligand is bound the reduction in fluorescence is less significant over time compared to the unbound state. b)  Normalised fluorescence over the course of a standard TRIC experiment

Where appropriate, Domainex can assess TRIC as an additional readout in parallel, but Spectral Shift is typically prioritised because it generally provides improved sensitivity, better signal-to-noise and faster plate acquisition.

MST: A Well-Known Solution-Phase Binding Method

MicroScale Thermophoresis (MST) is a well-established solution-phase method for measuring binding affinity and remains widely recognised across the drug discovery community. It measures ligand-induced changes in the movement of a fluorescently labelled molecule through a temperature gradient.

While Domainex has extensive experience with MST, our current assay development strategy typically prioritises Spectral Shift on the Dianthus platform because it offers practical advantages for many client projects, including higher sensitivity, improved signal-to-noise and greater suitability for medium-throughput workflows.

Our biophysics team will recommend the most appropriate assay format based on the target, ligand type, affinity range, sample availability and project goals. For most projects, this means starting with Spectral Shift, with TRIC or MST considered where they offer a specific technical advantage.

 

How We Support Your Binding Study

Our team works with you to select, optimise and interpret the most appropriate solution-phase binding assay for your target and project goals.

  1. Discuss your target, ligand type and project objectives
  2. Recommend the most appropriate assay format and labelling strategy
  3. Optimise assay conditions using minimal sample
  4. Measure binding across relevant compound concentrations
  5. Rank binders and interpret affinity data
  6. Recommend orthogonal validation where useful

Labelling Strategies 

Successful Spectral Shift, TRIC and MST assays depend on selecting a labelling strategy that preserves target behaviour while providing a robust fluorescent signal. Domainex can advise on the most suitable covalent or affinity-based labelling approach for your protein, RNA, complex or other biomolecule.

Covalent based dyes:
  • Maleimide
  • NHS
  • SNAP-Tag
Affinity based dyes:
  • Biotin
  • His-Tag
  • Human FC

Ready to De-risk Your Binding Study?

Spectral Shift-led solution-phase binding analysis gives drug discovery teams a practical way to confirm target engagement, rank compounds and prioritise the most promising binders using sensitive, low-sample assays. Our biophysics team can recommend the most appropriate assay format, labelling strategy and orthogonal validation plan for your target, ligand series and programme goals.
 

Frequently Asked Questions

When should I use Spectral Shift rather than MST or TRIC?

Domainex typically recommends spectral shift as a starting point for most binding studies because it provides a robust, sensitive and medium-throughput solution-phase readout across a broad range of target classes. TRIC and MST may still be considered where they offer a specific technical advantage or where an MST-based approach is specifically requested.

How much protein or biomolecule is needed?

One of the main advantages of Spectral Shift-led assay development is the low sample requirement compared with many traditional biophysical approaches. The amount required depends on the assay format, labelling strategy, affinity range and number of compounds or concentrations tested, and the Domainex team can advise on the most sample-efficient design.

Can these assays be used for fragment screening?

Yes. Spectral Shift is well suited to fragment screening and hit confirmation because it can detect weak binding interactions in solution while using relatively small amounts of material. It can also help rank fragment hits and prioritise compounds for follow-up using orthogonal methods where appropriate.

Can Spectral Shift, MST or TRIC be used with challenging targets?

These solution-phase assays can be useful for challenging systems where immobilisation-based methods may not be ideal, including protein complexes, RNA, membrane proteins, molecular glues and bifunctional ligands. Assay suitability depends on target quality, stability, labelling feasibility and the expected binding mechanism.

Do targets need to be labelled?

Most Spectral Shift, TRIC and MST assays require a fluorescently labelled biomolecule or affinity-based labelling strategy. Domainex can advise on covalent and affinity-based options designed to preserve target behaviour while generating a robust assay signal.

Can these methods confirm direct target engagement?

Yes. Spectral Shift, MST and TRIC are designed to measure direct interactions between ligands and biomolecules in solution. They can support target engagement confirmation, affinity measurement and compound ranking during hit identification, validation and optimisation.

Can the results be validated using other biophysical methods?

Yes. Where useful, Domainex scientists validate key findings with orthogonal techniques such as GCI/SPR, DSF or ITC. Our biophysics team can recommend an appropriate validation strategy based on the target, ligand series, affinity range and project objectives.

Case studies