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− | <p style="font-size:18px;text-align:left">Enzymatic colorimetric assays are used to determine the concentration of a chemical in a solution by the conversion of a chromogen substrate into a coloured product. We have engineered <i>Escherichia coli (E.coli)</i> BL21 (DE3) strain to express | + | <p style="font-size:18px;text-align:left">Enzymatic colorimetric assays are used to determine the concentration of a chemical in a solution by the conversion of a chromogen substrate into a coloured product. We have engineered <i>Escherichia coli (E.coli)</i> BL21 (DE3) strain to express alcohol oxidase (<a href="http://parts.igem.org/Part:BBa_K2092000" target="_blank">AOx</a>) from <i>Pichia pastoris</i> that will then be used in a cell-free colorimetric system. This method involves the usage of AOx to oxidise ethanol, producing hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) as a by-product. H<sub>2</sub>O<sub>2</sub> is used as an oxidising agent by horseradish peroxidase (HRP) to convert ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) to produce the colour change <sup>[1]</sup>. |
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Revision as of 22:56, 14 October 2016
Project Overview
Mechanism 1
Cell Free System
![Mechanism 2 overview diagram](https://static.igem.org/mediawiki/2016/8/86/T--Manchester--mechanism1_overview.png)
Enzymatic colorimetric assays are used to determine the concentration of a chemical in a solution by the conversion of a chromogen substrate into a coloured product. We have engineered Escherichia coli (E.coli) BL21 (DE3) strain to express alcohol oxidase (AOx) from Pichia pastoris that will then be used in a cell-free colorimetric system. This method involves the usage of AOx to oxidise ethanol, producing hydrogen peroxide (H2O2) as a by-product. H2O2 is used as an oxidising agent by horseradish peroxidase (HRP) to convert ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) to produce the colour change [1].
Mechanism 2
Inducible Gene Switch
![Mechanism 2 overview diagram](https://static.igem.org/mediawiki/2016/1/12/T--Manchester--mech2_overview.png)
The alc gene expression system is one of the most reliable chemically inducible gene switches for use in plants and fungus. This system relies on the ability of AlcR, an alcohol-activated transcription factor, to bind to its target alcA promoter (PalcA). Based on this, we have engineered E. coli K-12 derivative DH5α and BL21 to induce expression of chromoproteins when AlcR binds to the native PalcA and variant of PalcA ( PalcA(var)) in the presence of ethanol [2].
References
- Azevedo, A. M., Prazeres, D. M. F., Cabral, J. M., & Fonseca, L. P. (2005). Ethanol biosensors based on alcohol oxidase. Biosensors and Bioelectronics,21(2), 235-247.
- Panozzo, C., Capuano, V., Fillinger, S. and Felenbok, B. (1997) ‘The zinc binuclear cluster Activator AlcR is able to bind to single sites but requires multiple repeated sites for synergistic activation of the alcA gene in Aspergillus nidulans’, Journal of Biological Chemistry, 272(36), pp. 22859–22865.