To assure no influence of the reaction buffer on the ionisation process, an ammonium acetate buffer with a low buffer concentration was chosen. Therefore, the reaction was conducted in 10 mM ammonium acetate buffer (pH 6.5). Unfortunately, this makes it difficult to compare the kinetic parameters obtained with other data as no parameters acquired under similar conditions have been published so far. The assay was performed in glass HPLC vials and samples were introduced into the mass spectrometer using flow injection analysis (FIA), whereby the sample is injected into an eluent (Methanol:Water:Acetic acid 66:33:1) current. The reaction was started at the begin of the first equilibrium run by adding the enzyme to the reaction solution. Several experiments were conducted simultaneously.