Mass spectrometry (MS) binding assays are a highly versatile technique for gauging the affinity of a ligand for a target. This label-free screening approach has all the advantages of conventional radioligand binding assays without the need for handling radioactive material. The research group of Klaus T. Wanner, Ludwig Maximilians University, Munich, Germany, implemented MS binding assays to the serotonin transporter (SERT). The search for new SERT inhibitors as improved drugs is important, as SERT regulates serotonin levels in the synaptic cleft, and so it is the main target for treating depression, obsessive–compulsive disorder, and anxiety.

Wanner’s group demonstrated the feasibility of SERT MS binding assays by using (S)-fluoxetine as native (non-labeled) marker. The results of their experiments are in good agreement with corresponding radioligand binding assays. Hence, the developed label-free MS technique is an easy way to test potential inhibitors for their affinity toward SERT in screening campaigns.

• (S)- and (R)-Fluoxetine as Native Markers in Mass Spectrometry (MS) Binding Assays Addressing the Serotonin Transporter
  M. Hess, G. Höfner, K. T. Wanner,
  ChemMedChem 2011, 6(10).
  DOI: 10.1002/cmdc.201100251