Enzyme and reaction engineering of unspecific peroxygenase driven hydroxylation of butane (BUPOx)
This joint proposal of the working groups of Prof. Holtmann and Prof. Liese aims at the profound understanding of the influences and interactions of process parameters on the biocatalytic efficiency of the oxy functionalization of short chain alkanes. On the example of the asymmetric hydroxylation of butane to 2-butanol catalyzed by the recently emerging enzyme group, the unspecific peroxidases (UPO) detailed interdisciplinary process studies are carried out. The feasibility of the reaction system was already demonstrated in common preliminary research by the two groups in first bubble column experiments and at the same time the necessity for more detailed investigations to grasp the observed antagonistic effects. At first a model enzyme, the AaeUPO, will be characterized. Of particular interest is the stability regarding hydrogen peroxide feed rate and gassing effects from gaseous butane feed. To improve relevant selectivities a screening for new UPO variants (enantioselectivity) will be combined with reaction engineering, focusing on in situ product removal by extraction (process selectivity). As UPOs display a broad substrate scope, a “reversed” substrate screening is necessary to find suitable solvents that are not substrates at the same time. Lastly, promising UPO variants will be immobilized on a gas diffusion electrode that is integrated in the reactor. By this means new fundamental knowledge is generated in terms of overcoming limiting factors for hydroxylations catalyzed by UPOs.