Targeting OAS Enzymes with the Transcreener 2-5A OAS Assay

Discover OAS Modulators with the Transcreener 2-5A OAS Assay

The Transcreener OAS Assay measures the 2-5A produced by OAS1 (also known as 2'-5'-oligoadenylate synthetase 1) OAS2, or OAS3. By measuring the production of OAS researchers can effectively determine the activity of OAS enzymes. The assay provides a powerful tool to screen compound libraries for OAS modulators to help find new therapeutics for a variety of different conditions including autoimmune diseases.

The assay is currently available as a product and service performed in-house at BellBrook Labs. Please contact us for questions related to the assay or acquiring enzymes.

The Role of OAS1 In Innate Immunity

Double stranded RNA enters the cell from viral infection. As a first line of defense in the innate immune system, OAS1 is activated by viral double-stranded RNA. Upon activation, OAS1 synthesizes 2-5A from ATP which in turn activates RNase L. The result of this signaling event cleaves both viral and host RNA and in turn inhibition of protein synthesis in the cell, thus ending the replication of invading RNA viruses. Mutation or inadvertent stimulation can produce autoimmune conditions by activating the pathway inconsistently even while not in the presence of viral invaders.

Detection of 2-5A to Measure OAS Enzymatic Activity

Transcreener OAS1 Assay Schematic

In the presence of dsRNA OAS uses ATP to produce the messenger 2-5A. The assay uses a coupling enzyme which generates AMP from the 2-5A. The AMP is then measured by the proven Transcreener AMP/GMP Assay with an FP readout.


  • Measure Enzymatic Activity of OAS1, OAS2, or OAS3
  • Screen Compound Libraries for OAS Modulators
  • Quantify Inhibitor Potency
  • Inhibitor Selectivity Profiling


  • Designed as in homogenous, one-step format to enable reproducibility.
  • Robust Assay Z’ > 0.7 under initial velocity conditions
  • Far-red fluorescent readouts minimize compound interference

Mix-and-Read, HTS-Ready Assay, for Robust Screening

The Transcreener OAS Assay is in a, HTS-ready, mix-and-read format. Run your enzyme reaction, add Transcreener reagents, and read the plates. The assay is compatible with 96, 384, and 1536-well formats.

Enzyme Titration with the Transcreener OAS Assay - FP Readout

The assay demonstrates linearity when raw data is converted to the product formed using a standard curve. Linearity is shown under initial velocity conditions when raw data is converted to AMP formed as 2-5A is broken down by the detection reagents.

Human OAS1 Enzyme Titration

OAS1 Assay Enzyme Titration Raw Data

Data Converted to Product Formed

OAS1 Assay Enzyme Titration Converted Data

Screen for Inhibitors & Perform SAR

Transcreener Assays are designed for screening compound libraries in a high throughput format. Follow-up SAR can also be performed using the assay to determine inhibitor potency with ease.

Dose-Response with Suramin

OAS1 Assay Dose Response Suramin

IC50 = 0.162 µM

Robust Assay Yields Quality Data

Z’ measurements using optimized OAS1 reaction conditions indicate a robust assay.  Robust data like this is vital for sizeable high throughput screens that are difficult to complete due to the massive sample quantity.

Far-Red FP Readout Validated on Major Multimode Readers

Supplier Instrument FP Assays
bioteklogo TriStar²S LB 942 in review
Mithras² LB 943 in review
bioteklogo Cytation™ 5 validated
Cytation™ 3 validated
Cytation™ 1 validated
Synergy™ H1 validated
Synergy™ 2/H4/4 validated
Synergy™ HTX not capable
Synergy™ Neo 2 validated
BMGLABTECH Logo POLARstar® Omega validated
FLUOstar® Omega not capable
PHERAstar® FSX validated
PHERAstar® Plus/FS validated
CLARIOstar® /Plus validated
VANTAstar validated
MDS AT logo Analyst® GT/HT validated
Gemini® XPS/EM not capable
SpectraMax® M2/M2e not capable
SpectraMax® M5/M5e/FlexStation® 3 not capable
SpectraMax® Paradigm validated
perkinElmerLogo EnVision®/EnVision® Xcite validated
tecanLogo Infinite® M1000/M1000Pro/Safire2™ validated
Infinite® M200 not capable
Infinite® F500 validated
Infinite® F200/Ultraevolution contact us
Spark™ 10M validated

What's Included

What You Will Need

Transcreener OAS Assay Kits

* For custom or bulk orders (over 10,000 wells) please contact us ( for a quote.

Human OAS1 Enzyme

* For custom or bulk orders (over 10 μg) please contact us ( for a quote.

OAS1 Assay Services

Interested in moving your program forward, but don't want to bring an assay in-house? Our scientists can help! BellBrook scientists will use their extensive biochemistry and enzymology expertise to work with you and accelerate your OAS1 or innate immunity program.

Assay Development Services

Lead Discovery Services Include:

  • Inhibitor Screening – To identify or confirm activity with the target.
  • Inhibitor Potency Profiling – Dose-response with target and/or related proteins. Fast IC50 results.
  • Mechanism of Action Studies – Kinetic analysis to define the mode of inhibition.

Contact Us to Learn More

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