engleski

Mathematical modeling of DERA-catalyzed statin side-chain intermediate production

For the past few years aldolases, enzymes that catalyze one of the most powerful reactions for forming C-C bonds, have been getting a lot of attention in the production of statin side-chains, due to their ability to introduce two stereogenic centers in a single step. Namely, the current industrial production of the world"s most popular hypolipemic drugs – statins – is a laborious multi-step process carried out at very harsh conditions, which could be circumvented by the application of chemoenzymatic routes. In this work, the tandem aldol reaction of a protected aldehyde (PA) with two equivalents of acetaldehyde (AA) catalyzed by the DERA aldolase was examined. A two-step DERA-catalyzed side reaction of AA self- aldol addition also occurs by ultimately forming an AA trimer. The DERA enzyme was kinetically characterized, and a mathematical model of these reactions was developed and validated in batch reactors. The kinetic parameters of Michaelis-Menten kinetic models were estimated from the experimental data using the method of initial rate. The enzyme stability in different concentrations of AA was examined. The reaction was carried out in a batch (BR) and repetitive batch reactor (RBR) in order to obtain higher final product concentration. The reaction in RBR was conducted by three fresh substrate additions of same concentration as the initial once their concentration dropped zero, and a second, fresh addition of enzyme was added after third addition of substrates, due to prominent enzyme activity decrease. The enzyme stability in the presence of varying AA concentration was described by second-order kinetics, while the dependency of the deactivation constant on the AA concentration was described by second- order polynomial model. The results of the change of AA and AA trimer concentration over time indicate the existence of the retro-aldol reaction. The BR resulted in the production of approx. 28 g/L, while RBR of 80 g/L of final product. In both experiments, complete conversion of PA was achieved. High by-product concentration in both BR (8 g/L) and especially in RBR (56 g/L) was evident. Statistical analysis provided by Scientist software proved that the proposed model describes the experimental results well, and thus can be a useful basis for future predictions of this system.

mathematical modelling ; DERA ; biocatalysis ; statins

This work has received funding from the EU Horizon 2020 research and innovation programme under grant agreement 635595 "CarbaZymes".