title: Evaluation of ionic liquids as alternative solvents for aldolase activity: Use of a new automated SIA methodology.
abstract: An automated methodology is proposed for the evaluation of a set of ionic liquids (ILs) as alternative reaction media for aldolase based synthetic processes. For that, the effect of traditionally used organic solvents and ILs on the activity of aldolase was studied by means of a novel automated methodology. The implemented methodology is based on the concept of sequential injection analysis (SIA) and relies on the aldolase based cleavage of d-fructose-1,6 diphosphate (DFDP), to produce dihydroxyacetone phosphate (DHAP) and d-glyceraldehyde-3-phosphate (G3P). In the presence of FeCl3, 3-methyl-2-benzothiazoline hydrazine (MBTH) forms a blue cation that can be measured at 670nm, by combination with G3P. The influence of several parameters such as substrate and enzyme concentration, temperature, delay time and MBTH and FeCl3 concentration were studied and the optimum reaction conditions were subsequently selected. The developed methodology showed good precision and a relative standard deviation (rsd) that does not exceed 7% also leading to low reagents consumption as well as effluent production. Resorting to this strategy, the activity of the enzyme was studied in strictly aqueous media and in the presence of dimethylformamide, methanol, bmpyr [Cl], hmim [Cl], bmim [BF4], emim [BF4], emim [Ac], bmim [Cl], emim [TfMs], emim [Ms] and Chol [Ac] up to 50%. The results show that the utilization of ILs as reaction media for aldolase based organic synthesis might present potential advantages over the tested conventional organic solvents. The least toxic IL found in this study was cho [Ac] that causes a reduction of enzyme activity of only 2.7% when used in a concentration of 50%. Generally, it can be concluded that ILs based on choline or short alkyl imidazolium moieties associated with biocompatible anions are the most promising ILs regarding the future inclusion of these solvents in synthetic protocols catalyzed by aldolase.
authors.affiliation: REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira no 228, 4050-313 Porto, Portugal.
authors.forename: Edite
authors.initials: E
authors.lastname: Cunha
authors.affiliation: REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira no 228, 4050-313 Porto, Portugal. Electronic address: ppinto@ff.up.pt.
authors.forename: Paula C A G
authors.initials: PC
authors.lastname: Pinto
authors.affiliation: REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira no 228, 4050-313 Porto, Portugal. Electronic address: lsaraiva@ff.up.pt.
authors.forename: M Lúcia M F S
authors.initials: ML
authors.lastname: Saraiva
keywords: Aldolase activity; Ionic liquids; Organic synthesis; SIA