    4.4.1.21 | analysis |
rapid, selective, and sensitive liquid chromatography-tandem mass spectrometry assay for the simultaneous quantification of the metabolites and precursors of the activated methyl cycle. Analytes are extracted from Escherichia coli MG1655 and chemically derivatized as N(O,S)-iso-butyloxycarbonyl iso-butyl esters using iso-butyl chloroformate in an aqueous iso-butanol/pyridine environment. S-Adenosylmethionine, S-adenosylhomocysteine, S-ribosylhomocysteine, homocysteine, methionine, cystathionine, cysteine, and homoserine are quantified by liquid chromatography-positive ion tandem electrospray ionization mass spectrometry. Internal standards are isotopically labeled [13CD3]methionine and S-adenosylcysteine. Linearity of the assay is established up to a concentration of 700 microg/g cell dry weight for each analyte |
713738 |
