In Vitro Assays

Biochemical assays are essential tools to screen compounds that bind to target proteins with a defined mechanism. In recent years a large variety of enzyme/biochemical assays have been developed to discover and to optimize compounds that inhibit the activity of these targets. WuXi Biology is dedicated to providing open access and integrated platforms to support plate-based screening services, including HTS, hit identification, lead optimization, selectivity screening and early safety profiling, up to drug candidate selection.

Enzyme Assays

Assay Development

  • Strong expertise relating to enzymology in drug discovery.
  • Capabilities for assay development on diverse targets: kinase, phosphatase, ATPase, GTPase (KRAS) polymerase, dehydrogenase/reductase, protease, epigenetic enzymes (HMT, KDM, HDAC, Bromodomain), ligand-receptor (protein) binding and PPI.

Assay Formats

  • End-point assay & continuous assays
  • Plate-based screening platform
  • Major assay platforms: TR-FRET, FP, ADP-Glo, Z-Lyte , ELISA, absorbance, LC/MS

Compound Profiling

  • Weekly screening service to provide clients high quality, timely data with the ability to solve problems and communicate effectively 
  • Potency measurements across multiple target classes (IC50, Ki)

Inhibitor Characterization

  • Compound evaluation, as a part of SAR, to understand MOA of inhibitors, including mechanism of inhibition, time-dependent inhibition and reversibility of inhibition
  • Example of studying mechanism of inhibition
Enzymology, Kinase, phosphatase, ATPase, polymerase, protease, and epigenetic enzymes, ATP, titration
Enzyme inhibitor analysis, including Vmax, Km, Ki, substrate-inhibitor titration, reversible, time-dependent

Kinase Assays

As one of the important classes of drug target, Kinase remains an area of interest for both pharmaceutical industry and academia. To assist the efforts in kinase drug discovery, WuXi Biology offers high quality, time efficient and cost-effective kinase solution for assay development, high throughput screening (HTS) and selectivity profiling. WuXi Biology provides multiple cellular assay development formats to support different functional assessments of the drug candidates.

Assay Development

Assay development is applicable for a broad range of kinases involved in MAPK pathway, cell cycle, NF-kB pathway, AKT/PKB pathway, JAK/STAT, membrane receptor, etc.

  • Biochemical assay:
    • A variety of formats: TR-FRET (LANCE Ultra, LathaScreen, HTRF), Caliper, Luminescence (Kinase-Glo, ADP-Glo), LC-MS, Radiometric, IMAP, ADP-Quest, Z’ LYTE, etc.
    • Development includes routine assay optimization (enzyme titration, time course, Km determination etc.) and assay validation (DMSO tolerance, Z’ test, compound validation, etc.).

WuXi Biology also provides service for compound MOA study in the effort to further characterize the identified potent compounds.

Example of assay development

Results from various biochemical assay development for protein kinases.
(A) Establishment of initial velocity for the determination of kinase A ATP Km.
(B) ATP Km determination for kinase A using ADP Quest format.
(C) Kinase profiling-IC50 determination using Kinase Glo Plus.
Curve fit

ELISA Potency Assay

  • Cellular Assay
    • Activity evaluation: ELISA, AlphaLISA, Western Blot, LanthaScreen activity assay, Cisbio HTRF assay, Pathhunter kinase assay
    • Compound binding assay: ActivX assay, LanthScreen binding assay
    • Protein interaction detection: Cisbio HTRF, PathHunter binding assay
    • Cellular selectivity screen: ActivX assay, MSD
  • Compound Screening
    • We support HTS and routine SAR screening against enzyme targets using either WuXi Biology developed assays or assays transferred from clients.

Kinase Selectivity Profiling Services

  • Profiling format: Caliper, Kinase Glo Plus, ADP Glo
    • The diversified panel for profiling services.
    • Single dose measurement and IC50 determination
    • Single compound test and library screening
    • Data turnaround time: 1-2 weeks
Compound A selectivity profile against a panel of 30 kinases.

GPCR, Transporter and NHR

G-protein-coupled receptors (GPCRs) GPCR G-protein

GPCR Assays

G-protein coupled receptors (GPCRs) form the largest class of cell-surface receptors. Overall, there are ~ 800 GPCRs. Currently ~ 35% of all drugs approved by the FDA act at 108 unique GPCRs1.

1. Hauser et al. (2017). Trends in GPCR drug discovery: New agents, targets and indications Nature Reviews Drug Discovery 16(12): 829–842

Comprehensive In Vitro GPCR Services

  • Compound profiling:
    • Medchem, MoA studies
    • MTS and HTS
    • IND filing
  • Assay development & transfer
  • Safety/off-target screening
  • Stable GPCR cell line generation
  • Over 100 proprietary GPCR cell lines, covering 44 GPCR families (and corresponding assays)
  • GPCR assays for safety/off-target profiling (Read More)

Diverse Platforms

Binding Assays
Radioactive I-125, H-3Filtration
Tag-lite + HTRFHTRF
Fluorescence polarizationFP
Functional Assays
GTPrS S-35Filration
Reporter geneFluorescence
Transporter and NHR (Nuclear Hormone Receptor) Assays
Transporters and NRTransporter NR (human)Main organ class or systemRadioligand BindingFunction Assay
Estrogen receptorERCervix, endometriumyesReporter gene assay
Peroxisome proliferator activated receptor gammaPPARγAdipose tissueyesReporter gene assay
Progesterone receptorPRCervix, endometriumyesReporter gene assay
TransporterDATCNSyesDye Uptake
Transporter5HTTCNS, CVSyesDye Uptake
TransporterNETCNS, CVSyesDye Uptake
Steroid Nuclear ReceptorsAREndocrineyesReporter gene assay
Steroid Nuclear ReceptorsGREndocrine, immuneyesReporter gene assay

Radioligand binding and functional assays (Read More for Targets and Assays) 

WuXi Biology GPCR Cell Lines and Assays | Customized assays are routinely provided upon request.

View our platform of biophysical assays and structural biology services for GPCRs and membrane proteins by clicking HERE

Radioactive Assays

WuXi Biology Laboratories

  • 120 square meters laboratories
  • 6 regular radioisotopes are licensed: 14C, 3H, 32P, 33P, 35S, 125I
  • Multiple radiometric counters to support different purpose of assay formats
    • Microbeta , TriCarb, Topcount and Gamma counter

Assay Targets and Platforms


  • GPCRs (Click for list
  • Other Receptors (Click for list
  • Transporters (Click for list
  • Ion channels (Click for list
  • Enzymes
  • Lipids, carbohydrates
  • Metabolites
  • Epigenetic targets

Types of radioactive assay platforms

  • Filter binding assay
  • SPA (Scintillation Proximity Assay)/FlashPlate
  • Cellular uptake assay
  • Metabolic assay
  • High throughput screening (HTS)

Ion Channel

Ion channels are important drug targets because they play a crucial role in controlling a very wide spectrum of physiological processes, and also ion channels are closely related to drug safety. WuXi AppTec Biology has been providing ion channel services for over 10 years. We offer a broad portfolio of functional assessments on ion channel at various drug discovery stages to accelerate your new drug discovery progress.  

Ion Channel Drug Discovery Services

  • Compound screening: Ion channel HTS, support hit finding to lead optimization programmes
  • MOA studies for lead compounds: Conventional patch-clamp studies at cellular or tissue level, using stable cell lines expressing ion channels, native cells (dissociated DRG cells, primary cultured cortical or hippocampal neurons) and/or IPSC derived neurons or cardiomyocytes

Advanced Ion Channel Screening Capability and Capacity

  • Automated and manual patch-clamp instruments
  • Compound profiling | Technical platform:
    • Automated and conventional patch-clamp
    • FLIPR assays, ion channel HTS
  • Reagent generation
    • Ion channel stable cell line generation
    • Ion channel BacMam expression system construction

Ion Channel Expression System Generation

  • Ion channel stable cell line generation
  • Ion channel BacMam expression system construction

Cardiac Safety Services

  • hERG and other cardiac channel testing: ion channel cardiac safety panel (CIPA compliant)
  • Stem cell derived cardiomyocyte studies with MEA

Click here for more information about the cardiac safety services. 


ion channel, patch clamp, hERG, cardiomyocytes assessed with MEA, CIPA, and cardiac channel testing

Sodium channel IV curve obtained with QPatch 

GABA current recorded via manual patch clamp, using primary culture hippocampal neurons

GABAA current recorded from primarily cultured hippocampal neurons with manual patch-clamp

Using MEA to assess the effects of quinidine on stem cell derived ventricular cardiomyocytes

Effects of Quinidine on human stem cell derived ventricular cardiomyocytes recorded on MEA