In the continuously changing environment of drug development and molecular biology, sensitive and high-throughput kinase activity monitoring remains a key component of target validation and inhibitor screening.
Kinases, which catalyze the transfer of phosphate groups from ATP to protein, lipid, or nucleotide substrates, play a critical role in signal transmission, cell cycle control, and metabolic regulation.
Dysregulated kinase activity has been linked to a variety of human diseases, including cancers, autoimmune disorders, cardiovascular disease, and neurodegenerative ailments, due to its key role in cellular physiology.1,2
SwiftFluo® TR-FRET kinase kits provide a highly sensitive, selective, simple, and rapid assay platform to help researchers decode kinase biology while also expediting small molecule drug discovery and lead optimization.
These kits, based on advanced time-resolved fluorescence resonance energy transfer (TR-FRET) technology, are especially optimized for profiling 60+ tyrosine kinases (TKs), 150+ serine/threonine kinases (STKs), and 15+ cyclin-dependent kinases (CDKs), providing flexibility across diverse target classes and screening strategies.
Principles
The SwiftFluo® TK and STK platforms use a "sandwich" immunoassay method, with the enzyme phosphorylating a biotinylated substrate during the kinase reaction.
The phosphorylated product is subsequently recognized by a phospho-specific antibody tagged with Solar Eu (donor) and collected using a streptavidin-linked acceptor (HX or LA).
When the donor and acceptor are in close proximity, resonance energy transfer occurs, resulting in an emission of 620/665 nm. The strength of the TR-FRET signal is directly proportional to the level of phosphorylated substrate.
The SwiftFluo® CDK kits, on the other hand, use a streamlined dual-component system that includes a TR-FRET donor-labeled phospho-specific antibody and a directly acceptor-labeled protein substrate (Rb [S780] and ATF2 [T71]), allowing for the rapid and sensitive quantification of CDK target activity (CDK1, 2, 5, 9, etc.).
SwiftFluo® TR-FRET TKs kinase kit
Figure 1. The principle of SwiftFluo® TR-FRET TK activity detection. Image Credit: Sino Biological Inc.
SwiftFluo® TR-FRET CDKs kinase kit-Rb(S780) substrate
Figure 2. The principle of SwiftFluo® TR-FRET CDK activity detection. Image Credit: Sino Biological Inc.
Benefits of the SwiftFluo® kinase kits
SwiftFluo® kinase kits provide a homogeneous assay format for accurate measurement of kinase activity.
In contrast to typical FRET tests reliant on short-lived fluorescent dyes that frequently suffer from quick signal attenuation, strong background interference, and photobleaching under repeated excitation, TR FRET uses lanthanide donors such as europium (Eu) or terbium (Tb).
These donors have extremely long fluorescence lifetimes (up to 1-2 ms) and excellent photostability, practically eliminating signal loss due to photobleaching. Background autofluorescence from assay components and biological samples is significantly reduced by delaying excitation and emission detection.
With this low interference, TR FRET has significantly improved signal-to-noise ratios and provides consistent, reproducible readouts, ideal for high-throughput kinase profiling and inhibitor screening.
SwiftFluo® TR-FRET assays have many benefits over other detection methods:
- The wide dynamic range (3-5 logs) and excellent assay window (S/B ratio ~10) enable sensitive quantification of various kinase types.
- Solar Eu and Tb dyes exhibit fluorescence signal fading and photodegradation difficulties, but this dye maintains superior stability under altering pH, temperature, and ionic strength.
- The kits' low background fluorescence and negligible DMSO interference (≤2 %) make them ideal for small-molecule compound screening.
- Ratio-metric detection (665 nm / 620 nm) reduces pipetting errors and improves quantitative repeatability across wells.
- The homogeneous, no-wash format reduces manual processes and assay variability, allowing for high-throughput screening (HTS) in 96/384/1536-well formats.
- Rapid results (60 minutes incubation) with high reproducibility and Z' factors of ≥0.5, making it ideal for screening applications.
SwiftFluo® TR-FRET assays have several advantages over other platforms. They are not affected by kinase autophosphorylation, unlike ADP-Glo™ assays. Additionally, unlike ELISA or MSD, they do not require wash steps, resulting in a more efficient workflow and increased test throughput.
Applications
The SwiftFluo® TR-FRET kinase assay family is designed to enable a broad range of applications, including early-stage kinase profiling, HTS, and hit validation. With coverage of main kinase classes (TKs, STKs, and CDKs), the platform provides flexibility and scalability for a variety of drug development activities.
These kits have been previously validated with substrates, antibodies, and buffers tuned for over 200 kinases, including disease-relevant targets such as EGFR, FLT3, JAK2, BRK, AMPK, ROCK1, CDK1, CDK5, and many more.
TKs and STKs kits can be used to support a broad-spectrum kinase panel or a specialized substrate-based application.
The SwiftFluo® TR-FRET kinase kits are ideal for enzymatic activity validation, allowing researchers to characterize recombinant kinases and ensure lot-to-lot uniformity.
The kits enable reproducible dose-response tests with excellent signal stability for IC50 and EC50 assessments, making it easier to assess compound potency.
They are also suitable for developing a uniform screening platform in which the same assay format may be used for TKs, STKs, and CDKs, with optimum conditions specific to each kinase class to enable consistent kinase profiling.
In addition, the kits' uniform, no-wash structure and robust assay performance make them ideal for industrial HTS studies that require rapid triaging of chemical libraries.
The assay is fully compatible with microplate readers equipped with a TR-FRET detection module and can be scaled to 96-, 384-, and 1536-well plates, allowing for simple incorporation into automated screening workflows.
Featured kinase kits
Source: Sino Biological Inc.
| Cat. No |
Name |
| SFKA001 |
SwiftFluo® TR-FRET TKs kinase kit |
| SFKA002 |
SwiftFluo® TR-FRET STK discovery kinase kit |
| SFKA003 |
SwiftFluo® TR-FRET STK S1 kinase kit |
| SFKA004 |
SwiftFluo® TR-FRET STK S2 kinase kit |
| SFKA005 |
SwiftFluo® TR-FRET STK S3 kinase kit |
| SFKA006 |
SwiftFluo® TR-FRET CDKs kinase kit - Rb (S780) substrate |
| SFKA007 |
SwiftFluo® TR-FRET CDKs kinase kit - ATF2 (T71) substrate |
More products
Source: Sino Biological Inc.
| Cat. No |
Name |
| SFKA011 |
SwiftFluo® TR-FRET Enzymatic activity booster (EAB) |
| SFKA014 |
SwiftFluo® TR-FRET TKs substrate - biotin |
| SFKA015 |
SwiftFluo® TR-FRET BTKs substrate - biotin |
| SFKA016 |
SwiftFluo® TR-FRET JAKs substrate - biotin |
| SFKA017 |
SwiftFluo® TR-FRET FGFRs substrate - biotin |
Conclusion
SwiftFluo® TR-FRET kinase kits integrate cutting-edge detection technology with assay simplicity to provide a powerful toolkit for determining kinase activity, screening compounds, and optimizing leads.
With excellent sensitivity, broad kinase compatibility, and seamless HTS integration, these kits enable researchers to speed up discovery workflows and obtain high-confidence data across a wide range of therapeutic targets.
References
- Baldi, S., et al. (2025). Advancements in Protein Kinase Inhibitors: From Discovery to Clinical Applications. Research, 8. DOI: 10.34133/research.0747. https://spj.science.org/doi/10.34133/research.0747.
- Attwood, M.M., et al. (2021). Trends in kinase drug discovery: targets, indications, and inhibitor design. Nature Reviews Drug Discovery, [online] 20(11), pp.839–861. DOI: 10.1038/s41573-021-00252-y. https://www.nature.com/articles/s41573-021-00252-y.
About Sino Biological Inc.
Founded in 2007, Sino Biological is a global biotechnology company specializing in high-quality recombinant proteins, antibodies, and CRO services. Serving researchers in over 90 countries, Sino Biological supports basic research, drug discovery, vaccine development, and diagnostics through its comprehensive product portfolio, proprietary quality systems, and innovative research platforms.
Sino Biological's core business
Sino Biological is a leading global biotechnology supplier dedicated to high-quality research reagents and comprehensive CRO services. Its extensive product portfolio covers over 9,800 recombinant proteins, 15,000 antibodies, and 50,000 genes, all produced in-house. As a trusted CRO partner, Sino Biological specializes in customized recombinant protein and antibody production. It stands out with its robust high-throughput antibody production system, including HEK293/CHO and cell‑free platforms. This system enables rapid turnaround (as fast as 5 days), high-throughput production (> 10,000 Abs/month), and cost-effective solutions for global academic and pharmaceutical clients.
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