Jacob Skibsted Jensen

Process considerations for the asymmetric synthesis of chiral amines using transaminases

Biocatalytic transamination is being established as key tool for the production of chiral amine pharmaceuticals and precursors due to its excellent enantioselectivity as well as green credentials. Recent examples demonstrate the potential for developing economically competitive processes using a combination of modern biotechnological tools for improving the biocatalyst alongside using process engineering and integrated separation techniques for improving productivities. However, many challenges remain in order for the technology to be more widely applicable, such as technologies for obtaining high yields and productivities when the equilibrium of the desired reaction is unfavorable. This review summarizes both the process challenges and the strategies used to overcome them, and endeavors to describe these and explain their applicability based on physiochemical principles. This article also points to the interaction between the solutions and the need for a process development strategy based on fundamental principles. Biotechnol. Bioeng. 2011; 108:1479–1493.

Experimental determination of thermodynamic equilibrium in biocatalytic transamination

The equilibrium constant is a critical parameter for making rational design choices in biocatalytic transamination for the synthesis of chiral amines. However, very few reports are available in the scientific literature determining the equilibrium constant (K) for the transamination of ketones. Various methods for determining (or estimating) equilibrium have previously been suggested, both experimental as well as computational (based on group contribution methods). However, none of these were found suitable for determining the equilibrium constant for the transamination of ketones. Therefore, in this communication we suggest a simple experimental methodology which we hope will stimulate more accurate determination of thermodynamic equilibria when reporting the results of transaminase-catalyzed reactions in order to increase understanding of the relationship between substrate and product molecular structure on reaction thermodynamics.

Topology-optimized and dispersion-tailored photonic crystal slow-light devices

We review our work done for topology optimization of passive photonic crystal component parts for broadband and wavelength dependent operations. We show examples of low-loss topology-optimized bends and splitters optimized for broadband transmission and demonstrate the applicability of topology optimization for designing slow-light and/or wavelength selective component parts. We also present how the dispersion of light in the slow-light regime of photonic crystal waveguides can be tailored to obtain filter functionalities in passive devices and/or to obtain semi-slow light having a group velocity in the range ~(c0/15 - c0/100); vanishing, positive, or negative group velocity dispersion (GVD); and low-loss propagation in a practical ~5-15 nm bandwidth.