This thesis could show the potential of peptide microarrays as efficient tool for parallel profiling of various putative substrates for enzymes as well as binders for proteins. The comprehensive range of application of peptide microarrays could be demonstrated. By means of the same assay technology this work could identify binding specificities of readers and of diverse commercially available sequence specific antibodies, as well as the characterization of substrate specificities of various writers and erasers. Additionally, the cross-talk of posttranslational modifications for enzymatic activities could be identified by means of this assay technology. For selected proteins the results of the peptide microarrays were validated in homogeneous assays and characterized kinetically.