METHOD AND KIT FOR ISOTOPE-LABELLING OF A GLUTATHIONE-CONTAINING BIOLOGICAL SAMPLE FOR MASS SPECTROMETRY

摘要

The present invention provides a method of stabilising a biological sample comprising glutathione (GSH) and glutathione disulfide (GSSG), comprising a) providing the biological sample comprising GSH and GSSG, b) contacting GSH and GSSG of the biological sample with a maleimide to obtain maleimide-alkylated GSH, c) separating excess maleimide from maleimide-alkylated GSH and GSSG, d) contacting maleimide-alkylated GSH and GSSG with a reducing agent such as TCEP under conditions which allow reduction of GSSG by the reducing agent such as TCEP to obtain further GSH, and e) contacting maleimide-alkylated GSH and GSH with a heavy isotopologue of the maleimide to obtain a heavy isotopologue of the maleimide-alkylated GSH. Also provided is a stabilised biological sample containing maleimide-alkylated GSH and a heavy isotopologue thereof, as well as a mass-spectrometric method for quantifying maleimide-alkylated GSH and a heavy isotopologue thereof in a biological sample and a kit for stabilising a biological sample comprising GSH and GSSG for mass spectrometric analysis.