The self-assembled monolayer matrix assisted desorption ionization (SAMDI) technology relies on high density biochip arrays on microplates for immobilization of substrates and products of enzyme reactions, combined with MALDI-TOF mass spectrometry. All steps of the process are compatible with automated liquid handling in 384- and 1536-well format.
Assay volumes and throughput
Assay volumes can be as low as 1 µl, both with reactions in solution, or with assay components immobilized on 384-well or 1536-well microtiter plates. Together with fast readout times, this renders the process amenable to high throughput, enabling processing of >10,000 samples per day. Assay development fully considers enzyme kinetics to warrant robustness (Z’ routinely ~ 0.8) while maintaining sensitivity.
Application to histone methyltransferase PRMT1 enzymatic reaction
Shown in the figure is the application of the SAMDI technology to the detection of peptide methylation products through the histone methyltransferase PRMT1. After the enzymatic reaction, the peptidic analytes are attached to the monolayer on the gold surface and analyzed through MALDI-TOF mass spectrometry. The relative abundance of substrate, mono- and di-methylated products can be quantified and the PRMT1 enzyme kinetic can be followed over time (image courtesy of SAMDI Tech, Inc.)
|Enzyme families||Substrate types||Surface compatibility||Capture chemistry|
|De-methylases||Proteins||Cell lysates||Click, azide-alkyne|
|Kinases||Small molecules||Organics||Electrostatic interaction|
|and many more…|