Reverse micelles are self-organized aggregates formed by a surfactant in a non-polar solvent or oil. The presence of a water pool in the polar core of reverse micelles is of considerable advantage in protein extraction. A lot of researches have been done with ionic reverse micelles applied in protein extraction. However, this ability of non-ionic reverse micelles has not been fully understood and therefore requires more research. In this project, different surfactants (anionic AOT, cationic CTAB, non-ionic triblock L61 copolymer) were investigated for their ability to form RM and for their application in protein extraction. It was found that lysozyme could be extracted using an AOT RMS, but not with a CTAB RMS. For the first time, an aromatic solvent, p-xylene, was used for the extraction of lysozyme and it was found that the AOT in p-xylene RM system resulted in the higher lysozyme activity (73.81 %) compared to an AOT/isooctane RM system (43.2 %). The effect of different salts (KCl, KF, KBr) on the FE and BE of BSA was investigated using the CTAB in mixture of 1-bromooctane, 1-hexanol and petroleum ether. The results indicated that KCl gave the highest extraction efficiency of 64 % as compared to around 40 % with both cases of KF and KBr. The secondary structure of extracted BSA was maintained with KCl only. L61 pluronics polymers was investigated for its reverse micelles forming ability and it was established that small reverse micelles with a maximum W0 of 4 was formed. Because of the small size of L61 reverse micelles, lysozyme could not be extracted but was precipitated out when combined with the co-surfactant AOT. The activity of the recovered lysozyme from the precipitate was maintained (66% as compared with native lysozyme). Moreover, if L61 was used as a co-surfactant with AOT reverse micelles, extraction efficiency was improved (88 %) and the activity of the extracted ly-sozyme was increased (56 %) as compare to extraction with an AOT system alone (46 %). These studies thus gives useful insights in the role of individual and mixed surfactant systems in the extraction and precipitation of proteins.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:732818 |
| Date | January 2015 |
| Creators | Pham, Thi Minh Hai |
| Contributors | George, Daliya A. ; Nielsen, Birthe |
| Publisher | University of Greenwich |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://gala.gre.ac.uk/18122/ |
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