Interrogating TREX1 with the Transcreener dAMP Exonuclease Assay

TREX1 Assay System

The TREX1 Assay System includes TREX1 enzyme, DNA substrate, assay plates, and buffer components required for a TREX1 reaction to produce dAMP. The Transcreener dAMP Exonuclease Assay (sold separately) measures dAMP to determine enzymatic activity. These measurements allow researchers to screen compound libraries for modulators to help find new disease therapies.

The Transcreener dAMP Exonuclease Assay is not included in the assay system but is available for separate purchase through BellBrook Labs. For dAMP assay ordering information, please view Transcreener dAMP Exonuclease Assay.

The Comprehensive Approach to Measure TREX1 Enzymatic Activity

TREX1 Assay System Comprehensive Overview

Assay System includes enzyme, substrate, & buffers for the TREX1 reaction. Transcreener's dAMP Assay measures corresponding dAMP activity. 

Robust Assay Yields Quality Data

The TREX1 Assay System used with the Transcreener dAMP assay produces robust results amenable to HTS. Z’ measurement using optimized TREX1 assay conditions (n=16). Z’ = 0.88.

Screen for Inhibitors & Perform SAR

The TREX1 Assay System used with the Transcreener dAMP assay is designed to screen compound libraries in a high throughput format to identify potential inhibitors. Follow-up SAR can also be performed using the assay to determine inhibitor potency with ease.

Trex1 dose-response curves v3

The Transcreener dAMP Exonuclease Assay allows selectivity profiling for TREX1. Suramin IC50 = 3.0 µM.

Detection of dAMP to Measure TREX1 Activity - FP Readout

The enzyme buffer includes 10 mM Tris pH 7.5, 7.5 mM MgCl2, 0.005% BSA, and 0.01% Brij-35. Here we use 35 nM ISDna. The Detection mix included 20 μg/mL dAMP antibody, 2 nM dAMP Alexa 633 tracer, and 1X Stop & Detect Buffer B in 10 μL. The TREX1 enzyme reaction took place for 60 minutes at 30°C. The Detection Mix was added and incubated for 90 minutes at room temperature and read with a CLARIOstar plate reader. Linearity is shown here when raw data is converted to dAMP formed using a standard curve.

TREX1 Enzyme Titration

TREX1 Assay Enzyme Titration

Linear Response

TREX1 Assay Enzyme Titration Product Formed

Overview of Transcreener's dAMP Exonuclease Assay (Sold Separately)


The Transcreener dAMP Exonuclease Assay directly measures dAMP produced during the biological functions like the degradation of DNA. Transcreener dAMP technology uses polyclonal mouse antibodies that selectively bind to dAMP and a far-red fluorescent tracer. dAMP produced displaces the tracer, changing the fluorescent properties and providing a readout.

It is an easy-to-use, mix-&-read, HTS-ready assay that yields robust results. All you need to do is perform the enzyme reaction, add Transcreener reagents, and read your plates. It is available with an FP fluorescent readout.

BellBrook's Recombinant TREX1 Enzyme

Active, human Three Prime Repair Exonculease 1 enzyme, His-tagged protein expressed and purified from baculovirus-infected insect cells. The enzyme has been thoroughly validated with Transcreener dAMP Exonculease Assay Kit. For specific activity, please refer to the Certificate of Analysis for each individual enzyme lot. Purity is >90% in a 50 mM Tris, 500 mM NaCl, and 20% glycerol buffer composition (pH 8.0). Currently used with the Transcreener assay at a concentration between 0.06 - 0.52 nM in a 10 μL reaction.

TREX1 Enzyme Schematic v2

TREX1 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 TREX1 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.
  • Residence Time Measurements – Determination of koff using ‘jump dilution’ enzymatic assay method.
  • Mechanism of Action Studies – Kinetic analysis to define the mode of inhibition.

Contact Us to Learn More

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What's Included

What You Will Need

TREX1 Assay System

* For custom or bulk orders (over 100,000 wells) please contact us ( for a quote.

Transcreener dAMP Exonuclease Assay Kits

* For custom or bulk orders (over 100,000 wells) please contact us ( for a quote.

TREX1 Enzyme Ordering Information

* For custom or bulk orders (over 100 µg) please contact us ( for a quote.

Related Resources

A Guide to Measuring Drug-Target Residence Times with Biochemical Assays

During drug development initiatives, analysis of drug-target residence times can improve efficacy, increase therapeutic window, and reduce the risk of premature focus on candidate compounds that are likely to have undesirable effects. This guide provides technical background on concepts and techniques for use of Transcreener biochemical assays to measure drug-target residence times, along with examples and case studies. 

Learn more including:

  • The basics of residence time and its importance to drug discovery
  • A comparison of methods used for residence time determination
  • Using the jump-dilution method with Transcreener biochemical assays
  • Data analysis used to accurately determine residence time
  • Examples of measuring residence time for kinases, phosphodiesterases, and glycosyltransferases
Drug-Target Residence Time Guide

Enter your contact info and learn how to determine drug-target residence times and improve your lead discovery with this 12-page guide!

A Guide to Navigating Hit Prioritization After Screening Using Biochemical Assays

So you have performed your screen. What's next? This guide is focused on how biochemical assays are used for characterizing and prioritizing compounds following a primary screen with an enzyme target- whether using high throughput or virtual screening. A typical screening funnel illustrates the utility of biochemical assays for a variety of prioritization applications. 

Here we will discuss strategies for hit-to-lead selection including:

  • Assay Considerations
  • Hit Confirmation
  • Running a Dose-Response
  • Compound Triaging
  • Hit Expansion
  • Mechanism of Action Studies
  • Residence Time Measurement
BellBrook's Hit Prioritization Guide

Enter your contact info and learn how to prioritize hits and improve your lead discovery with this 9-page guide!

TREX1 As a Therapeutic Target

TREX1 is a crucial component of the innate immune response acting as the main exonuclease responsible for degrading cytosolic DNA. Reduction of cytosolic DNA leads to inactivation of the cGAS/STING Pathway, which is essential for intrinsic antitumor immunity. As a result, TREX1 plays a pro-tumorigenic role in cancer, and its inactivation is a promising strategy for future monotherapy and combination treatments.

The Discovery of TREX1 antagonists to reign in overactivity requires selective technologies that can help assess the ability to interact with the target. Robust, HTS-ready assays that are accurate yet flexible provide a powerful tool to accelerate discovery.