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

Transcreener 2-5A OAS Assay

Transcreener OAS Assay measures the 2-5A produced by OAS1 (2'-5'-oligoadenylate synthetase 1) OAS2, or OAS3. These measurements allow researchers to effectively determine the activity of the OAS enzyme. The assay provides a powerful tool to screen compound libraries for OAS modulators to help find new therapies for disease. 

The kit comes complete with the detection reagents required to measure activity. OAS enzyme is not included in the inhibitor screening assay kit. Please contact us for questions related to acquiring the enzyme.

This assay is designed to be used with purified enzyme preparations. Transcreener assays are not validated with cell lysates, blood, serum, or other biological samples.

How Does This OAS Assay Work?

The Transcreener OAS Assay determines OAS enzyme activity by using a coupling enzyme that converts 2'-5'A produced by OAS1 to the products AMP and ATP. AMP can be measured using the trusted Transcreener AMP2 Assay components. The assay provides a universal method to assess activity of any AMP-producing enzyme. 

Transcreener OAS Assay technology uses a simple but highly effective method that consists of an antibody selective to AMP and a far-red fluorescent tracer. AMP produced in the reaction competes with the tracer changing the fluorescent properties and providing fluorescent readout. 

The OAS assay is available with FP readout. It is a simple mix-and-read format. Perform your enzyme reaction, add the detection reagent, and measure. The simplicity of the system yields robust results that also makes it extremely amiable to HTS. 

Detection of 2-5A to Measure OAS Enzymatic Activity

Fluorescent Polarization (FP)

Transcreener OAS1 Assay Schematic

In the presence of dsRNA OAS uses ATP to produce the messenger 2-5A. The assay uses a coupling enzyme to generate AMP from 2-5A. AMP is measured by the Transcreener AMP/GMP Assay.


  • 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

Easy-to-Use, Mix-and-Read, HTS-Ready Assay

Run your enzyme reaction, add Transcreener reagents, and read your plates. The OAS assay is compatible with 96, 384, and 1536-well formats. 

Transcreener Mix and Read Assay

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. Z' shown here = 0.87. 

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

Linear Response

Linear Response Data OAS Assay

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

BellBrook Lab's Recombinant OAS1 Enzyme

Active, full-length human 2'-5' oligoadenylate synthetase 1 enzyme, His-tagged protein expressed and purified from E.coli. The enzyme has been thoroughly validated with Transcreener 2-5A OAS Activity Assays. For specific activity, please refer to the Certificate of Analysis for each individual enzyme lot. Purity is >95% in a 20 mM Tris-HCl pH 8.0, 10% glycerol, 1 mM DTT buffer composition. Currently used with the Transcreener assay at a concentration between 3 and 16 nM.

OAS1 Enzyme

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

Please fill out the form below. We will respond quickly to get the conversation moving and learn how we can help. We keep things discrete, confidential, and professional.

Far-Red FP Readout Validated on Major Multimode Readers

SupplierInstrumentFP Assays
TriStar2S LB 942In Review
Tristar 5In Review
Mithras2 LB 943In Review
CytationTM 5Validated
CytationTM 3Validated
CytationTM 1Validated
SynergyTM H1Validated
SynergyTM 2/H4/4Click Me ArrowValidated
SynergyTM HTXNot Capable
SynergyTM Neo 2Validated
POLARstar® OmegaClick Me ArrowValidated
FLUOstar® OmegaNot Capable
PHERAstar® FSXClick Me ArrowValidated
PHERAstar® Plus/FSClick Me ArrowValidated
CLARIOstar® /PlusClick Me ArrowValidated
VANTAstarTMClick Me ArrowValidated
SenseIn Review
Analyst® GT/HTClick Me ArrowValidated
Gemini® XPS/EMNot Capable
SpectraMax® M2/M2eNot Capable
SpectraMax® M5/M5e/FlexStation® 3Not Capable
SpectraMax® ParadigmClick Me ArrowValidated
SpectraMax® iD3/iD5Click Me ArrowValidated
SpectraMax® i3xClick Me ArrowValidated
EnVision®/EnVision® XciteClick Me ArrowValidated
Infinite® M1000/M1000Pro/Safire2TMClick Me ArrowValidated
Infinite® M200Not Capable
Infinite® F500Click Me ArrowValidated
Infinite® F200/UltraevolutionClick Me ArrowContact Us
SparkTM 10MClick Me ArrowValidated

What's Included

What You Will Need

Transcreener OAS Assay Kits

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

Human OAS1 Enzyme

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

Cat. No.Product DescriptionPriceAdd to Cart
2249Recombinant OAS1 Enzyme, Active, Human, Full-Length, 10 µg$439.00Add to Cart

Interconnections Between the DNA Damage Response and Innate Immunity

There is extensive crosstalk between the DNA damage response (DDR) pathways and innate immune pathways. Both the individual pathways and the interconnections between them are a focus for exciting new small molecule drug therapeutics that target cancers and debilitating autoimmune disorders. The Transcreener HTS Assay platform accelerates these efforts by providing a robust and easy-to-use biochemical assay to measure activity of key enzymes in the innate immune and DDR pathway.

In this guide, we provide an overview of the DDR and innate immune pathway, and describe Transcreener Assays and Assay Systems for key therapeutic targets. The enzyme targets discussed include:


  • POLQ
  • WRN
  • PARP1
  • PARG
  • DNA PK

Innate Immunity

  • cGAS
  • TREX1
  • TBK1
  • IKKβ
  • IRAK4
  • ENPP1
  • CD38
  • OAS-1
  • RIG-1/MDA5
  • DDX3
  • CD39
  • CD73
DNA Damage Response and Innate Immunity Preview

The Role of OAS1 As a Therapeutic Target

Double-stranded RNA enters the cell from viruses. As a first line of defense, viral double-stranded RNA activates OAS1. OAS1 then synthesizes 2-5A from ATP, which activates RNase L. This signaling cleaves both viral and host RNA leading to inhibition of protein synthesis. The replication of invading RNA viruses ends.

Mutation or inadvertent stimulation of OAS1 can produce autoimmune conditions by activating the pathway inconsistently, even while not in the presence of viral invaders. Because of this, OAS1 is an interesting target in drug discovery.

The Transcreener OAS Assay is an excellent tool for researchers examining the therapeutic effects of OAS1.