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SwiftFluo® TR-FRET Kinase Kits: Empowering Drug Discovery with Sensitivity, Versatility, and Scalability

SwiftFluo® TR-FRET Kinase Kits: Empowering Drug Discovery with Sensitivity, Versatility, and Scalability-feature-image

Introduction

In the rapidly evolving landscape of drug discovery and molecular biology, sensitive and high-throughput detection of kinase activity remains a cornerstone for target validation and inhibitor screening. Kinases, which catalyse the transfer of phosphate groups from ATP to protein, lipid, or nucleotide substrates, are key regulators of signal transduction, cell cycle control, and metabolic regulation.

Given their central role in cellular physiology, dysregulated kinase activity is implicated in a broad range of human diseases, including cancers, autoimmune disorders, cardiovascular diseases, and neurodegenerative conditions 1,2.

To support researchers in decoding kinase biology and accelerating small molecule drug discovery and lead optimisation, we provide a highly sensitive, specific, simple, and rapid assay platform. Built upon advanced time-resolved fluorescence resonance energy transfer, these kits are specifically optimised for profiling 60+ tyrosine kinases (TKs), 150+ , and 15+ cyclin-dependent kinases (CDKs), offering flexibility across diverse target classes and screening strategies.

Principles

The SwiftFluo® TK and STK platforms adopt a ‘sandwich’ immunoassay approach: during the kinase reaction, the enzyme phosphorylates a biotinylated substrate. The phosphorylated product is then recognised by a phospho-specific antibody labelled with Solar Eu (donor), and captured via a streptavidin-linked acceptor (HX or LA). The donor and acceptor, when brought into proximity, enable resonance energy transfer upon 320/340 nm excitation, emitting at 620/665 nm. The intensity of the TR-FRET signal directly correlates with the level of phosphorylated substrate.

On the other hand, the SwiftFluo® CDK kits utilise a streamlined dual-component system, which features a TR-FRET donor-labelled phospho-specific antibody and a directly acceptor-labelled protein substrate (Rb [S780] and ATF2 [T71]), enabling a fast and sensitive quantification of the activity of CDK targets such as CDK1, 2, 5, 9, etc.

SwiftFluo® TR-FRET TKs kinase kit

Figure 1. The principle of SwiftFluo® TR-FRET TK activity detection

SwiftFluo® TR-FRET CDKs Kinase Kit-Rb(S780) substrate

Figure 2. The principle of SwiftFluo® TR-FRET CDK activity detection

Advantages

They offer a homogeneous assay format tailored for robust kinase activity quantification. Unlike conventional FRET assays that rely on short‑lived fluorescent dyes, which often suffer from rapid signal attenuation, high background interference, and photobleaching under repeated excitation, TR‑FRET employs lanthanide‑based donors such as europium (Eu) or terbium (Tb).

These donors exhibit exceptionally long fluorescence lifetimes (up to 1–2 ms) and high photostability, effectively eliminating signal loss caused by photobleaching. By introducing a time delay between excitation and emission detection, background autofluorescence from assay components and biological samples is largely suppressed. As a result, TR‑FRET significantly improves signal‑to‑noise ratios and delivers stable, reproducible readouts that are well suited for high‑throughput kinase profiling and inhibitor screening.

Compared to other detection methods, SwiftFluo® TR-FRET assays offer several critical advantages:

  • Wide dynamic range (three to five logs) and excellent assay window (S/B ratio ~10) allow for sensitive quantitation across diverse kinase types.
  • Superior stability under varying pH, temperature, and ionic strength, with no fluorescence signal fading or photodegradation issues observed with Solar Eu or Tb dyes.
  • Low background fluorescence and minimal DMSO interference (≤2%) make the kits suitable for small-molecule compound screening.
  • Ratio-metric detection (665nm/620nm) effectively minimises pipetting errors and enhances quantitative reproducibility across wells.
  • Homogeneous, no-wash format minimises manual steps and assay variability, ready for high-throughput screening (HTS) in 96/384/1536-well formats.
  • Rapid results (60 minutes incubation) with robust reproducibility and Z’ factors typically ≥0.5, ideal for screening applications.

Importantly, SwiftFluo® TR-FRET assays avoid certain pitfalls of other platforms: unlike ADP-Glo™ assays, they are not confounded by kinase autophosphorylation; and unlike ELISA or MSD, they do not require wash steps, streamlining workflow and significantly enhancing assay throughput.

Applications

The SwiftFluo® TR-FRET kinase assay series is designed to support a wide range of applications from early-stage kinase profiling to HTS and hit validation. With coverage across major kinase classes (TKs, STKs, and CDKs), the platform offers flexibility and scalability for various drug discovery programmes.

These kits come pre-validated with substrates, antibodies and buffers optimised for over 200 individual targets, including disease-relevant targets such as EGFR, FLT3, JAK2, BRK, AMPK, ROCK1, CDK1, CDK5, and many more. TKs and STKs kits support either a general kinase panel with broad-spectrum substrates or a focused application with specific substrates.

The SwiftFluo® TR-FRET kinase kits are well-suited for enzymatic activity validation, enabling researchers to characterise recombinant kinases or confirm lot-to-lot consistency. For IC50 and EC50 determination, the kits allow reproducible dose–response measurements with excellent signal stability, facilitating the evaluation of compound potency.

They are also ideal for establishing a standardised screening platform, where the same assay format can be applied to TKs, STKs, and CDKs, with optimised conditions tailored to each kinase class, to support consistent kinase profiling. Furthermore, the homogeneous, no-wash format and robust assay performance make the kits particularly attractive for industrial HTS studies, where rapid triaging of compound libraries is essential. The assay is fully compatible with microplate readers with a TR-FRET detection module and scalable to 96-, 384-, and 1536-well plates, facilitating seamless integration into automated screening workflows.

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Conclusion

SwiftFluo® TR-FRET kinase kits combine cutting-edge detection technology with assay simplicity, delivering a powerful toolset for kinase activity measurement, compound screening, and lead optimisation. With high sensitivity, broad kinase compatibility, and seamless HTS integration, these kits empower researchers to accelerate discovery workflows and generate high-confidence data across a wide range of therapeutic targets.

Reference

  1. Baldi, S., Long, N., Ma, S., Liu, L., Al-Danakh, A., Yang, Q., Deng, X., Xie, J., & Tang, H. (2025). Advancements in Protein Kinase Inhibitors: From Discovery to Clinical Applications. Research (Washington, D.C.), 8, 0747. https://doi.org/10.34133/research.0747
  2. Attwood, M. M., Fabbro, D., Sokolov, A. V., Knapp, S., & Schiöth, H. B. (2021). Trends in kinase drug discovery: targets, indications and inhibitor design. Nature reviews. Drug discovery, 20(11), 839–861. https://doi.org/10.1038/s41573-021-00252-y

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