Method for determining the substrate specificity of an enzyme

The invention relates to a method for determining the substrate specificity of an enzymatic activity comprising the following steps: providing an assembly comprising a plurality of amino acid sequences on a planar surface of a support material, whereby the amino acids are directionally immobilized; contacting and/or incubating of an enzymatic activity with the assembly; and detection of a reaction between one of the amino acid sequences that are immobilized on the assembly and the enzymatic activity. According to the invention, during the reaction of the enzymatic activity with the assembly, a change in the molecular weight of at least one of the amino acid sequences takes place.