Our group started with steady-state methods to study enzymatic activity by spectrophotometry and fluorimetry and expanded in the last years the methodology to study also transient kinetics. The photometers and fluorimeters are adapted with 6 or 8-cell changers, thermostats, Peltier temperature controllers and thermal incubation chambers for up to 60 cuvettes to facilitate multiple measurements. In a first round the pH
dependency (pH profile, pH optima) of purified enzymes or enzyme variants are determined and stable assay conditions established. Then the determination of KM and Vmax (kcat) values follows. For special mechanistic questions our stopped-flow spectrophotometer is used. The high-throughput screening of mutagenesis libraries is performed on two plate-readers using the 96- or 384 well-plate format.