Modelling the reaction course of N-acetylneuraminic acid synthesis from N-acetyl-d-glucosamine—new strategies for the optimisation of neuraminic acid synthesis

Abstract

In this work, a model describing the complete enzyme catalysed synthesis of N-acetylneuraminic acid (Neu5Ac) from N-acetyl-D-glucosamine (GlcNAc) is presented. It includes the combined reaction steps of epimerisation from GlcNAc to N-acetyl-D-mannosamine (ManNAc) and the aldol condensation of ManNAc with sodium pyruvate yielding Neu5Ac. The model is expedient to predict the reaction course for various initial and feed concentrations and therefore to calculate reaction times and yields. The equilibrium constants calculated from the kinetic constants via the Haldane relationship correspond with experimental values very well (0.26 calculated and 0.24 experimental value for the epimerisation, 27.4 l mol(-1) calculated and 28.7 l mol(-1) experimental for the aldol condensation). The actual relevance of the model is shown by a scale-up. Using the model, an optimisation of reaction conditions in consideration of different targets is possible. Exemplarily, it is presented how the optimal ratio of the two enzymes in the reaction can be determined and how the composition of the reaction solution in a fed-batch reactor can be designed to meet downstream processing needs.

Reactive extraction of N-acetylneuraminic acid—A new method to recover neuraminic acid from reaction solutions

“…A high yield of neuraminic acid can be achieved with an excess of GlcNAc as well [10]. Two model solutions with concentrations according to fed-batch reactions simulated in [10] were prepared.…”

“…A high yield of neuraminic acid can be achieved with an excess of GlcNAc as well [10]. Two model solutions with concentrations according to fed-batch reactions simulated in [10] were prepared. The first solution contained an excess of GlcNAc (0.32 mol/l GlcNAc, 0.05 mol/l ManNAc, 0.20 mol/l Pyr and 0.25 mol/l Neu5Ac), the second, an excess of pyruvate (0.10 mol/l GlcNAc, 0.01 mol/l ManNAc, 0.35 mol/l Pyr and 0.23 mol/l Neu5Ac).…”

“…1 However, both reaction steps suffer from low yields due to the thermodynamic equilibrium. The equilibrium constant of the GlcNAc epimerisation is 0.24, the one of the aldol condensation is 28.7 l/mol [10]. The conversion can be improved by adding an excess of pyruvate, usually 2-10-fold compared to ManNAc [11][12][13].…”

Potenzial von Prozessintegration mit Adsorbern zur Herstellung seltener Monosaccharide – eine modellbasierte Untersuchung

“…[35]. In allen Fällen konnten die publizierten kinetischen Parameter [33][34][35] Desweiteren sind noch mit Borsäure funktionalisierte Harze erhältlich, die eine höhere Selektivität als die Ionentauschermaterialien aufweisen, aber dafür sehr stark durch kleine Beladungskapazitäten eingeschränkt sind [39]. Eine weitere Möglichkeit, Monosaccharide selektiv zu trennen, besteht in der Extraktion mit Borsäure oder anderen Carriern [16 -19].…”

Methodological Approach for Modeling of Multienzyme in-pot Processes

“…The important pharmaceutical intermediate N-acetyl-D-neuraminic acid (Neu5Ac) is produced due to its anti-viral, anti-cancer and anti-inflammatory effects [5]. One innovative option for producing this compound is by combining two enzymes in a single reactor [3].…”