Chiral seperations by enzyme enhanced ultrafiltration : fractionation ofracemic benzoin

Download

index.pdf

Date

2006

Author

Ölçeroğlu, Ayşe Hande

Metadata

Show full item record

Item Usage Stats

225
views

68
downloads

In this study, a methodology for separation of chiral molecules, by using enhanced ultrafiltration system was developed. Benzoin was the model chiral molecule studied. In the scope of developing this methodology, some parameters were investigated in the preliminary ultrafiltration experiments in order to set the operation conditions for enhanced ultrafiltration experiments. Due to the slight solubility of benzoin in pure water, 15% (v/v) Polyethylene glycol (PEG 400) and 30 % (v/v) Dimethyl sulfoxide (DMSO) were selected as cosolvents. Because of the high retention capacity of RC-10000 Da membranes for benzoin, a membrane saturation strategy was developed. In polymer enhanced ultrafiltration (PEUF) experiments bovine serum albumin (BSA) was used as ligand. Effects of ligand concentration and pH on total benzoin retention and on enantiomeric excess (ee %) were investigated. Benzoin concentration was almost kept constant at ~10 ppm and ~50 ppm for 15% (v/v) PEG 400 and 30 % (v/v) DMSO cosolvents, respectively. It was observed that the increase either in pH or in BSA concentration yielded an increase in total benzoin retention. In 15% (v/v) PEG 400-water, with BSA concentration of 10000 ppm, at pH 10, total benzoin retention reached to 48.7%. For this cosolvent, at different pH values and at different BSA concentrations, all ee % values were about or less than 10%. When 50000 ppm BSA was dissolved in 30 % (v/v) DMSO-water, total benzoin retention increased to 41.3% at pH 10 and ee % reached 16.7 % at pH 11. In enzyme enhanced ultrafiltration (EEUF) experiments, specific to benzoin, apo form of Benzaldehyde Lyase (BAL, E.C. 4.1.2.38) was used as ligand. These experiments were performed with constant ~ 10 ppm benzoin concentration in only 15% (v/v) PEG 400 water solvent. Effect of BAL concentration on total benzoin retention and ee% was investigated. It was found that; for all the studied BAL concentrations in the range of 650- 1936 ppm total benzoin retention and ee % were kept almost constant at ~75% and ~60%, respectively.

Subject Keywords

Chemical Engineering.

URI

http://etd.lib.metu.edu.tr/upload/12607460/index.pdf
https://hdl.handle.net/11511/16312

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Kinetic studies for the production of tertiary ethers used as gasoline additives Boz, Nezahat; Doğu, Timur; Department of Chemical Engineering (2004) In the present study, the kinetics studies for etherification reactions were investigated in detail. In the first phase of present study, different acidic resin catalysts were prepared by the heat treatment of Amberlyst-15 catalysts at 220°C at different durations of time and also by the synthesis of sulfonated styrene divinylbenzene cross-linked resins at different conditions. A linear dependence of reaction rate on hydrogen ion-exchange capacity was in 2M2B+ethanol reaction. However, in the case of 2M1B+e...
Bioreaction network flux analysis for industrial microorganisms: A review Çalık, Pınar (Walter de Gruyter GmbH, 2002-01-01) This review focuses on the analysis of the bioreaction networks of the microorgansims used in fermentation processes, by metabolic flux analysis that is the novel tool of biochemical reaction engineering, required for the quantitative analysis of cell metabolism which is under the control of the cell physiology. Metabolic flux analysis (MFA) is based on calculation of intracellular reaction network rates through various reaction pathways either theoretical or by using elaborate experimental data on uptake, ...
Bioprocess development for therapeutical protein production Çelik Akdur, Eda; Çalık, Pınar; Department of Chemical Engineering (2008) In this study, it was aimed to develop a bioprocess using the Pichia pastoris expression system as an alternative to the mammalian system used in industry, for production of the therapeutically important glycoprotein, erythropoietin, and to form stoichiometric and kinetic models. Firstly, the human EPO gene, fused with a polyhistidine-tag and factor-Xa protease target site, in which cleavage produces the native termini of EPO, was integrated to AOX1 locus of P. pastoris. The Mut+ strain having the highest r...
Dynamic and steady-state analysis of oxidative dehydrogenation of ethane Karamullaoğlu, Gülsün; Doğu, Timur; Department of Chemical Engineering (2005) In this research, oxidative dehydrogenation of ethane to ethylene was studied over Cr-O and Cr-V-O mixed oxide catalysts through steady-state and dynamic experiments. The catalysts were prepared by the complexation method. By XRD, presence of Cr2O3 phase in Cr-O; and the small Cr2O3 and V2O4 phases of Cr-V-O were revealed. In H2-TPR, both catalysts showed reduction behaviour. From XPS the likely presence of Cr+6 on fresh Cr-O was found. On Cr-V-O, the possible reduction of V+5 and Cr+6 forms of the fresh sa...
Metal polymer composite nanofiber production by electrospinning Karakoç, Nihan; Gündüz, Güngör; Department of Chemical Engineering (2009) This study aims synthesis of metal/polymer one dimensional nanostructures by micelle formation, reduction, and electrospinning route, and to analyze the morphological characteristics of composite nanofibers. The study was carried out in three main steps. First, the reverse micelle structures were established between the anionic surfactant and the metal ion. The surfactant acts as an agent to bind metal ions together so that the arrangements of metal ions can be controlled in the solution. As the surfactant ...

Citation Formats

A. H. Ölçeroğlu, “Chiral seperations by enzyme enhanced ultrafiltration : fractionation ofracemic benzoin ,” M.S. - Master of Science, Middle East Technical University, 2006.