Enzymatic synthesis of stable isotope-labeled SAM for screening hMAT2A inhibitors by using matrix-assisted laser desorption/ionization mass spectrometry

A high-throughput method was developed for screening human MAT2A (hMAT2A) inhibitors by using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS). The stable isotope deuterium-labeled S-adenosylmethionine (SAM-D₃) was enzymatically synthesized by hMAT2A using L-Met-D₃ and ATP as substrates and used as the internal standard for the enzyme activity assay, which could significantly improve the quantitative accuracy of high-throughput screening.