A Homogenous, Universal Enzymatic Methyltransferase Assay for HMTs

AptaFluor – Leveraging the Power of Aptamers for Drug Discovery

Epigenetic regulation has been shown to be a contributing factor in a variety of diseases. The discovery of methyltransferase inhibitors is currently an area of intense activity. Methyltransferase enzymes methylate a variety of substrates using S-adenosylmethionine (SAM) as the methyl donor leaving the common product S-adenosylhomocysteine (SAH).

The AptaFluor SAH Methyltransferase Assay uses a natural occurring aptamer, or riboswitch, that selectively binds with SAH, the invariant product of methyltransferase reactions. The exquisite affinity and selectivity of the riboswitch combined with a positive TR-FRET signal enable screening and profiling of methyltransferases with unparalleled sensitivity.

By directly detecting SAH in a homogenous format, it is possible to perform screening and enzymatic studies with virtually any methyltransferase. The assay can be used as a tool to aid researchers in hit identification and characterization in a quest to develop new methyltransferase inhibitors as treatments for disease.

Direct Detection of SAH with a TR-FRET Readout


The most sensitive HTS methyltransferase assay available with an LLD of 0.6 nM SAH. This dramatically reduces enzyme usage and allows the assay to be run at or below Km for SAM.

Use with Physiological SAM Concentrations Lower than 100nM


Outstanding reagent and signal stability reduces assay variability and allows for automated workflows.


Excellent Z’ under a variety of assay conditions.

PRMT4 enzyme with 0.2 uM or 2 uM SAM and histone substrate as positive controls. PRMT4 and histone substrate as negative control.

Simple Mix-and-Read

The AptaFluor SAH Methyltransferase Assay is in a simple, mix & read format. Run your enzyme reaction, add quenching reagent, add AptaFluor reagents, and read your plates.

Compatible with a Variety of MTase Acceptor Substrates

Toleration of MT acceptor substrates. 100 nM SAH-SAM standard curves were set up in the presence of nucleosomes (10 ng/μL), histone H3-3 (3 ng/μL), Histone H3 (1-21) peptide (10 μM) and Poly d (I-C) (2.5 mU/μL); control wells lacked a MT substrate.

Universal Assay – Use with Virtually Any Methyltransferase

Far Red TR-FRET Readouts Validated on Major Multimode Readers

AptaFluor SAH Methyltransferase Assay Kits

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

In addition to our Methyltransferase Assays, Bellbrook Labs also offers the following products and services to aid in the drug discovery process: