How COVALfinder® assays work

COVALfinder® is a highly tuned and optimized TR-FRET Binding Kinetic Assay based on the binding and displacement of an active-site directed fluorescent probe.

Real-time binding of the fluorescent probe is detected using a labeled anti-tag antibody, which binds to the target of interest. The binding of the fluorescent probe and labeled antibody to the target increases the TR-FRET signal, whereas the displacement of the fluorescent probe with a compound decreases the TR-FRET signal.

To ensure that our kinetic assays consistently deliver the highest quality data we always introduce up to 48 controls and a reference compound in each analysis.

Our services

Inactivation Kinetics

COVALfinder® is a robust kinetic platform that delivers all key inactivation (kinact, kinact/KI, T1/2) and affinity (KI) parameters for irreversible binders.

Binding Mechanism

Our kinetic platforms enable comprehensive analysis of reversible, reversible covalent and irreversible compounds, elucidating binding mechanism and measuring all kinetic and affinity parameters that define the drug-target interaction.


  • Easier decision-making: Ideal hit-to-lead and lead optimization tool to rank and develop promising irreversible compounds or reversible compounds that trigger conformational changes in the target.
  • Selectivity profiling for irreversible drugs: Evaluating inactivation efficiency (kinact/KI) accurately defines the time-dependent effects of covalent binding and enables the safety profile of irreversible drugs to be more rigorously assessed.
  • Thorough mechanistic profiling: Our assays provide detailed insights into the mechanistic characteristics of reversible, reversible covalent, and irreversible compounds.
  • Build better models: PK/PD models that integrate kinetics better predict target engagement, drug dose and treatment schedule.

    Features and benefits

    Reliable: In depth studies demonstrate concordance with literature values.

    There is a very good correlation between the kinact, KI and kinact/KI values of 21 irreversible inhibitors with 5 different targets obtained from our assays and those obtained from activity assays reported in the literature1-8.  Moreover, our assays provide reliable results regardless of the magnitude of the value measured.

    Figure 1. COVALfinder® is a reliable method. Graph. Correlation of 21 irreversible inhibitors with 9 different targets for efficiency (kinact/KI) values obtained with COVALfinder® and those reported in the literature. The plot displays the Pearson correlation coefficient (r) and p-value.

    We are experts in kinetic profiling

    Enzymlogic is a world leading analytical CRO, expert in generation and interpretation of kinetic data. We are proud to serve the smallest biotech innovators through to 10 of the world’s top 20 Pharma organizations, supporting drug hunters in their search for the most promising compounds in early discovery.


    1. Barf T. et al. (2017) J Pharmacol Exp Ther. 363(2):240-252.
    2. Bradley M. et al. (2017) AACR Annual Meeting.
    3. Brameld K.A. et al (2017) J Med Chem 10;60(15):6516-6527.
    4. Fassunke J. et al. (2018) Nat Commun. . 9(1):4655.
    5. Guo Y. et al. (2019) J Med Chem 12;62(17):7923-7940.
    6. Kwiatkowski N. et al. (2014) Nature. 511(7511):616-20.
    7. Lategahn J. et al. Chem Sci. 10(46):10789-10801.
    8. Liclican A. et al. (2020) Gen Subj 1864(4):129531.
    9. Malona J. et al (2022) Transl Res 249:49-73.
    10. Shanhu H.S. et al. (2019) Cancer Res. 79(13):3479-3491.
    11. Schwartz P.A. et al. (2014) Proc Natl Acad Sci U S A. 111(1):173-8.
    12. Turner T. et al (2023) 75th Annual Meeting of the American Academy of Neurology (AAN).
    13. Watterson S.H. et al. (2019) J Med Chem 11;62(7):3228-3250.
    14. Zapf C. W. et al. (2012) J Med Chem 26;55(22):10047-63.
    15. Zhang T. et al (2016) Nat Chem Biol. 12(10):876-84.
    16. Zhong Y. et al. (2015) J Biol Chem 6;290(10):5960-78.

    Accurate: Kinetic and affinity values are precise regardless of magnitude across a broad dynamic range.

    All our assays go through a rigorous establishment and validation process prior to use and ongoing assay performance is closely monitored to ensure they meet the highest of standards. COVALfinder® provides precise and reproducible KI, kinact and kinact/KI readouts, regardless of the magnitude of the values, in just a single assay.

    Figure 2. COVALfinder® provides accurate and reproducible results with a wide dynamic range. KI, kinact and kinact/KI values of 90 inhibitors and 17 different kinases from two independent experiments are shown on scatter plots with the axes in logarithmic scale. Each point represents an inhibitor-kinase interaction (165 interactions total). The plots display the Pearson correlation coefficient (r) and p-value.

    Sensitive: Our flexible and highly sensitive assays enable the identification and discrimination of a wide spectrum of compounds.

    COVALfinder® is a flexible and highly sensitive platform that uses low protein concentrations (from picomolar to low nanomolar), precise TR-FRET readouts and continuous measurements that enables the identification and discrimination of a wide spectrum of compounds:

    • Slow to rapid binders
    • Weak to potent binders.

    Robust and reproducible: Our assays show outstanding robustness and reproducibility between plates and days.

    The high and sustained stability of our assays guarantees reproducible and robust results over time.

    • Outstanding reproducibility between plates and days.
    • Enables data to be interpreted with confidence.
    • High Z-values ensure low false positive/negative rates.

    Our assays ensure robust measurement over time

    Figure 2. COVALfinder® enables data to be interpreted with confidence. Typical signal-to-background and Z-values obtained with COVALfinder® assays. S/B (blue) and Z-values (purple) were calculated based on 48 control wells over 8 hours.
    Figure 3. COVALfinder® provides highly robust measurements over time. Z-values from 94 independent assays spanning a period of 12 months. Z-values were calculated for each time point in a kinetic assay and averaged over the 4-hour duration.

    Our assays are highly reproducible between plates and days

    Figure 4. COVALfinder® provides outstanding reproducibility between plates and days.  Profiling of a reversible reference compound against 1 target over a six-month period. Analysis of the affinity (Kd) and kinetic constants (k1, k2) taken from 3 different compound, enzyme, probe and antibody lots demonstrate less than 5-fold variance.

    Rapid turnaround and cost effective: We are committed to delivering rapid and reliable data turnaround, on time and to budget, helping you keep your programs on track.

    Quality data, delivered on schedule

    We are laser focused on rapid and reliable data delivery, with a keen eye on timelines and budgets.

    • Standard data turnaround for study requests is 10 business days from compound receipt.
    • Expedited turnaround is available for regularly scheduled ongoing screening programs.

    We offer flexible solutions

    Together we will define the best way to collaborate through:

    • Ready-to-use or user-defined assays.
    • User-defined screening concentrations.
    • Bespoke assay development.
    • Flexible service models to support your discovery goals and maximize program success rates.
    • Direct contract, sub-contract via your principal CRO service provider or using outsourcing services (including Scientist and Science Exchange).

    List of targets ready to use

    Our expertise extends beyond kinases to GPCR and other target types.

    Search our database to discover whether your target is:
    • May be possible: We have a strong track record of achievement where others fail! Contact us to find out more.
    • Clear line of sight: Establishment requires finalization / validation, which typically takes 2-4 weeks to complete.
    • Good to go: Data within 2 weeks of compound receipt.

    * Full length and partial length forms are available.

    Target name Alternative names KINETICfinder COVALfinder
    ALK ALK, CD246, NBLST3 Good to go May be possible
    ALK1 (ACVRL1) ALK1, ALK-1, ACVRLK1, HHT, HHT2, ORW2, SKR3, TSR-I Good to go May be possible
    AMPK (A2/B1/G1) PRKAA2, PRKAB1, PRKAG1 Good to go May be possible
    ARAF A-RAF, ARAF1, PKS2, RAFA1 Good to go Good to go
    AXL JTK11, UFO Good to go May be possible
    BLK MODY11 Good to go May be possible
    BRAF V600E B-RAF1, B-raf, BRAF1, NS7, RAFB1 Good to go Good to go
    BRAF* B-RAF1, B-raf, BRAF1, NS7, RAFB1 Good to go Good to go
    BTK (activated) AGMX1, AT, ATK, BPK, IGHD3, IMD1, PSCTK1, XLA Good to go Good to go
    BTK (non-activated) AGMX1, AT, ATK, BPK, IGHD3, IMD1, PSCTK1, XLA Good to go Good to go
    CDK1/cyclin B CDC2, CDC28A, P34CDC2 Good to go Good to go
    CDK12/cyclin K CRK7, CRKR, CRKRS Good to go Good to go
    CDK13/cyclin K CDC2L, CDC2L5, CHDFIDD, CHED, hCDK13 Good to go Good to go
    CDK16/cyclin Y PCTK1, PCTAIRE, PCTAIRE1, PCTGAIRE, Good to go May be possible
    CDK7/cyclin H/MNAT CAK, CAK1, CDKN7, HCAK, MO15, STK1, p39MO15 Good to go Good to go
    CDK9/cyclin T1 C-2k, CDC2L4, CTK1, PITALRE, TAK Good to go Good to go
    CHEK2 (CHK2) CHK2, CDS1, HuCds1, LFS2, PP1425, RAD53, hCds1 Good to go May be possible
    CK1e (CSNK1E) CKIe, CKIepsilon, HCKIE Good to go May be possible
    CLK2 CDC like kinase 2 Good to go May be possible
    CRAF (RAF1) CMD1NN, CRAF, NS5, Raf-1, c-Raf Good to go Good to go

    How can we help?

    Our experienced project manager will work with you to identify the best way forward for your project.