Protein Engineering von Enzymen des Hydantoinase Prozesses Proteindesign Dihydropyrimidinase Molekulardesign Hydantoinase Prozess Carbamoylase Selektionsassay hydantoinase process selection assay protein engineering hydantoinase Carbamoylases and hydantoinases are industrially used in the hydantoinase process for synthesis of enantiopure amino acids. Using a hydantoin racemase enables a theoretical yield of 100%. This thesis aimed at the protein engineering of the partaking enzymes in order to allow for new substrates. The carbamoylase from A. aurescens was used in a gene shuffling experiment with the closely related beta ureidopropionases from S. kluyveri and A. tumefaciens. Furthermore rational design based on docking experiments was performed. Based on this targeted mutations as well as focused libraries were created in the carbamoylases active site. The acceptance of ß amino acid derivatives could be achieved. The active site of a hydantoinase from Ochrobactrum spec. was enlarged using rational design in order to achieve reactivity towards 5 5 disubstituted hydantoins. Activity was monitored used a multi step assay system. This system was based on a growth assay relying on ammonia starvation an NADH assay with glutamate dehydrogenase as coupling enzyme and direct HPLC detection.