The aim of this thesis was the enrichment of specific enzymes of the plant metabolism. Capture Compound Mass Spectrometry (CCMS) enabled the enrichment and detection of some members of S-Adenosyl-L-methionine or -homocysteine interacting proteins directly from crude extracts of Arabidopsis thaliana. In case of the three O-methyltransferases (OMTs), AtOMT1, AtCCoAOMT1 and AtTSM1 the organ and developmental specific distribution was proven according to the literature. The simultaneous development of nitrocatechol probes based on inhibitors of the mammalian Catechol OMTs, which are similar to the plant cation-dependent caffeoyl-CoA OMT-like proteins. Here, first enrichment experiments indicated a tentatively differentiation between cation-dependent and cation-independent OMTs. Furthermore, one member of the CCoAOMTs, AtCCoAOMT3, was barely detectable in roots by CCMS. Confirmatively a low transcript level was obtained by qRT-PCR. Biochemical analysis revealed phenylpropanoids as potential substrates of this protein. The corresponding T-DNA insertion line showed a reduced germination under salt stress conditions.