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Lead Discovery Services

BioAssay Systems has developed a range of high-throughput assays for drug targets. Our lead discovery services include, but are not limited to, hit-to-lead profiling and structure-activity relationship (SAR) studies.

Enzyme Inhibitor Screening

Our enzyme inhibitor screening services are optimized for modern lead discovery. Examples include evaluation of test compounds in regards to their activating (EC50) or inhibitory (IC50) effects on target enzyme(s) of interest,  and determination of their mode of action.
BioAssay Systems has developed and validated a variety of proprietory methods for follow-up study and HTS screening of kinase inhibitors. More details
Arginase is a drug target for various diseases, such as cancer, hypertension, atherosclerosis, myocardial ischaemia, congestive heart failure, and diabetes mellitus. More details
Protein tyrosine phosphatase 1B (PTP1B) is a key regulator and primary drug target for type 2 diabetes and obesity. It is also involved in liver regeneration, drug-induced liver disease, non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma. More details
Monoamine oxidase is involved in removing the neurotransmitters norepinephrine, serotonin and dopamine from the brain. Monoamine oxidase inhibitors (MAOIs) were the first type of antidepressant developed. More details
Acetylhydrolase is the primary cholinesterase that catalyzes the breakdown of acetylcholine and other choline esters that function as neurotransmitters. Acetylcholinesterase inhibitor is a drug that inhibits the breakdown of acetylcholine, thus increasing both the level and duration of action of the neurotransmitter acetylcholine. More details
Aldehyde Dehydrogenases (ALDHs) are a family of enzymes crucial to alcohol metabolism, catalyzing the breakdown of acetaldehyde. Elevated levels of ALDHs have also been associated to certain cancer types. Cancer Stem Cells (CSCs) with heightened levels of ALDHs have shown enhanced survival mechanisms leading to resistance to chemotherapy and radiation. More details
Farnesyl Transferase (EC (FTase) catalyzes the transfer of a farnesyl isoprenyl group to a cysteine residue fourth from the C-terminus of certain proteins, such as Ras, Rho, Rab, other Ras-related small GTP-binding proteins, and other targets. More details
Poly(ADP-Ribose) Polymerase [EC] is involved in single-stranded DNA break repair. It is integral to a programmed cell death model based on caspase cleavage. More details
Nitric Oxide Synthase ( catalyzes the formation of nitric oxide, a reactive radical, which plays an important role in many key physiological functions such as synaptic plasticity in the CNS and blood pressure regulation. More details
Urokinase (uPA, Urokinase plasminogen activator) ( is a key serine protease involved in the degradation of the extracellular matrix that catalyzes the conversion of plasminogen to active plasmin. More details
  • Acid Phosphatase
  • Aconitase
  • Alkaline Phosphatase
  • Amylase
  • Aspartate Transaminase
  • ATP-Citrate Lyase
  • Catalase
  • Creatine Kinase
  • Diamine Oxidase
  • Fumarase
  • Glucose Oxidase
  • Glucose-6-Phosphate Dehydrogenase
  • Glutamate Dehydrogenase
  • Glutathione Peroxidase
  • Glutathione Reductase
  • Glutathione S-transferase
  • Glyoxalase
  • Invertase/Sucrase
  • Isocitrate Dehydrogenase
  • Lactate Dehydrogenase
  • Lipase
  • Malate Dehydrogenase
  • Mannosidase
  • Myeloperoxidase
  • Neuraminidase
  • Phosphatase
  • Phospholipase D
  • Pyruvate Kinase
  • Sorbitol Dehydrogenase
  • Superoxide Dismutase
  • Urease
  • Xanthine Oxidase
If the enzyme you are interested in is not listed here, please email or call 1-510-782-9988 x 2 with your enzyme of interest and we will evaluate the project feasibility.

Signal Transduction and Drug Discovery

BioAssay Systems’ signal transduction and drug screening services are for evaluating changes in cell signaling as a result of exposure to test compounds. The services allow the screening of phosphorylation status modulators in important cell signalling pathways.


  • ERK Phosphorylation Status
    The mitogen-activated protein kinase (MAPK/ERK) pathway plays a key role in cell proliferation, differentiation and migration. The MAPK/ERK cascade presents many interesting drug targets for the development of cancer therapies. More details

  • AMPK Phosphorylation Status
    The 5-AMP-activated protein kinase (AMPK) is a key sensor of intracellular energy balance. Its activation is caused by a number of factors such as muscle contraction, starvation, or hypoxia. More details

  • NFκB Phosphorylation Status
    Nuclear factor-kappa B (NFκB) is a transcription factor that plays a central role in many physiological processes (e.g. inflammation, tumorigenesis, and apoptosis). More details

We routinely determine the test compound’s reactivity with different cell species, phosphorylation kinetics and the IC50 of activation or inhibition of the cellular pathway.

Please email or call us at +1-510-782-9988 ext 2 to discuss your service needs.

Mitochondrial Membrane Potential

Mitochondrial membrane potential is an key component of cell’s bioenergetics. We have successfully developed high-throughput assays and offer services for mitochondrial membrane potential in living mammalian cell cultures and in permeabilized yeast cells. More details.
Please email or call us at +1-510-782-9988 ext 2 to discuss your service needs.

ADMET: Absorption, Distribution, Metabolism, Excretion, and Toxicity

BioAssay System’s ADMET services are ideal for early stage drug discovery and specialized for evaluating test compounds as drug candidates. Screen for leads by testing for absorption, distribution, metabolism, excretion, and toxicity.


The solubility of a drug compound plays a significant role in absorption and is an important factor to consider during development. Quantitative measurement of compound solubility is an ideal early test to perform when screening for potential drug candidates.


Most drugs must pass through membrane barriers to reach their target. We offer quantitative measurement of compound permeability. More details.
  • Blood Brain Barrier (BBB) Permeability Inquire
  • Gastrointestinal (GI) Permeability Inquire
  • Skin Permeability Inquire


Toxicity is a crucial factor to test when evaluating test compounds as potential drug candidates. In most cases, test compounds should not be detrimental to the health of the cells they are treating. BioAssay Systems offers various methods to assess in vitro cell viability: ATP level, release of LDH and reduction capacity. More details
Please email or call us at +1-510-782-9988 ext 2 to discuss your service needs.

Select Publications by BioAssay Systems' Scientists

Rommel Mallaria, Elissa Swearingenb, Wei Liu, Arnold Ow, Stephen W. Young and Shu-Gui Huang* (2003) “A Generic High- throughput Screening Assay for Kinases: Protein Kinase A as an Example”. J. Biomol. Screen. 8: 198-204.

Catherine A. Hong, Elissa Swearingen, Rommel Mallari, Xiong Gao, Zhaodan Cao, Anne North, Stephen W. Young and Shu-Gui Huang* (2003) “Development of A High-Throughput Time-Resolved Fluorescence Resonance Energy Transfer Assay for TRAF6 Ubiquitin Polymerization”. Assay and Drug Development Technologies 1: 175-180.

Shu-Gui Huang* (2002) “Development of A High-throughput Screening Assay for Mitochondrial Membrane Potential in Living Cells”. J. Biomol. Screen. 7: 383-389.

Ellyn Farrelly, M. Catherine Amaral, Lisa Marshall and Shu-Gui Huang* (2001) A high-throughput assay for mitochondrial membrane potential in permeabilized yeast cells. Analytical Biochemistry 293(2):269-276.

Tony Smith, John Chan, Donna Oksenberg, Roman Urfer, Dave Wexler, Arnie Ow, Liping Gao, Alanna McAlorum, and Shu-Gui Huang* (2004). A High-Throughput Turbidometric Assay for Screening Inhibitors of Protein Disulfide Isomerase Activity. J. Biomol. Screen. 9(7): 614-620.

David S. Wexler, Liping Gao, Francisco Anderson, Arnold Ow, Laszlo Nadasdi, Alanna McAlorum, Roman Urfer, and Shu-Gui Huang* (2005). “Linking Solubility and Permeability Assays for Maximum Throughput and Reproducibility”. J. Biomol. Screen. 10(4): 383-390.

Shu-Gui Huang (2005) “Progress from HTS to HTL: Current Strategies in Drug Lead Discovery” Review article in Trends in Pharmaceutical Research 1: 5-10.

David S. Wexler, Shu-Gui Huang, Roman Urfer (2004). “Replumbing the Pipeline: A small, biopharmaceutical company’s strategy for integrating lead optimization and ADMET screening”. Current Drug Discovery, May 2004: 35-38.

Songzhu An, Gene Cutler, Jack Jiagang Zhao, Shu-Gui Huang, Hui Tian, Wanbo Li, Lingming Liang, Mike Rich, Amy Bakleh, Juan Du, Jin-Long Chen and Kang Dai (2001) Identification and Characterization of a melanin-concentrating hormone receptor. Proc. Natl. Acad. Sci. 98: 7576-7581.

Shu-Gui Huang, Donna Oksenberg, Roman Urfer (2005). “High-throughput Turbidometric Assay for Screening Inhibitors of Protein Disulfide Isomerase Activity”. US 6,977,142.

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