Biocatalytic synthesis of a biodegradable chelant (S,S-EDDS)
Integration of life sciences & engineering
Keynote Lectures: Theme-5
Keywords: Biocatalysis, sustainable bioprocesses, biodegradable chelant
Helen E M Law1 and John M Woodley2
1Department of Biochemical Engineering, University College London, London WC1E 7JE, UK
2Department of Chemical Engineering, Technical University of Denmark, Lyngby DK-2800, Denmark.
In recent years, interest in biocatalysis to assist in the synthesis of non-pharmaceutical targets has grown as focus on achieving more sustainable processes has increased [1]. Much has been made of the bioprocess conditions (mild temperatures and pressures in an aqueous environment). Additionally the possibility of creating biodegradable products is also attractive from a green standpoint and in this paper we will report work to devise a biocatalytic process producing a biodegradable product.
S,S-ethylenediamine-N,N’-disuccinic acid (S,S-EDDS) is a biodegradable, hexadentate chelant with similar chelation ability to EDTA, capable of reducing heavy metal build up in the environment [2]. It can be produced biocatalytically from ethylenediamine and fumaric acid by a two step, two enzyme pathway [3].
The biocatalytic route to S,S-EDDS is characterised by competition of fumarase and metabolism for fumaric acid, inhibition of EDDSase by fumaric acid, low catalyst concentrations from fermentation, a chemical side reaction to the incorrect intermediate enantiomer and equilibrium constants close to unity. A reaction model of the biocatalytic process, its side reactions and energy balances was set up and formed the basis of a sensitivity analysis, which with appropriate process metrics and associated hurdles, such as product concentration, enantiomeric excess, purity, rate of reaction and enzymatic efficiency, provided a method by which various process routes could be analysed and evaluated.
[1] Meyer et al (1997) Chimia, 51, 287.
[2] Schowanek et al (1997) Chemosphere, 34, 2375.
[3] Takahashi et al (1999) Biosci. Biotechnol. Biochem., 63, 1269.
Keynote lecture (theme-5)
Presented Thursday 20, 09:45 to 10:30, in session Keynote Lectures: Theme-5 (T5-K1, K2).
