Investigation of high molecular weight amine donors for the process intensification in chiral amine synthesis with transaminases The synthesis of several bioactive compounds and active pharmaceutical ingredients relies on the development of general and efficient methods to prepare optically pure amines. Transaminases are industrially relevant enzymes and are useful for synthesizing a large number of compounds that contain a chiral amine functionality. Although the immense potential associated to the use of these biocatalysts the equilibrium position is often unfavorable for amine synthesis. The use of an excess of amine donor compared to the ketone substrate combined with selective removal of the formed product can help in overcoming this limitation. This work mainly focused on broadening the application of membrane based in situ product recovery (ISPR) techniques for the transaminase catalyzed synthesis of chiral amines. The overall work was designed around the implementation of amine donors possessing considerably larger molecular ‘size’ compared to commonly used amine donors. To clearly distinguish these molecules from traditional donor amines we designate them as High Molecular Weigh amine donors. With a molecular weight between 400 and 1500 g mol in contrast to traditional donor amines HMW amine donors enable a size based separation between amine donor and amine product molecules. HMW amines provided in excess for thermodynamic equilibrium shifting can thus be simply retained by a size exclusion mechanism by commercial membranes while the smaller product amines are permeated. Therefore ... Amine Enzyme asymmetric synthesis Asymmetric synthesis Biocatalysis Chiral amine Enzyme In situ product recovery Membrane Transaminases