Continuous biotransformation of pyrogallol to purpurogallin using cross-linked enzyme crystals of laccase as catalyst in a packed-bed reactor
✍ Scribed by J Jegan Roy; T Emilia Abraham
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 2006
- Tongue
- English
- Weight
- 124 KB
- Volume
- 81
- Category
- Article
- ISSN
- 0268-2575
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✦ Synopsis
Abstract
Cross‐linked enzyme crystals (CLEC) of laccase were prepared by crystallizing laccase with 75% (NH~4~)~2~SO~4~ and cross‐linking using 1.5% glutaraldehyde. The cross‐linked enzyme crystals were further coated with 1 mmol L^−1^ β‐cyclodextrin by lyophilization. The lyophilized enzyme crystals were used as such for the biotransformation of pyrogallol to purpurogallin in a packed‐bed reactor. The maximum conversion (76.28%) was obtained with 3 mmol L^−1^ pyrogallol at a residence time of 7.1 s. The maximum productivity (269.03 g L^−1^ h^−1^) of purpurogallin was obtained with 5 mmol L^−1^ pyrogallol at a residence time of 3.5 s. The productivity was found to be 261.14 g L^−1^ h^−1^ and 251.1 g L^−1^ h^−1^ when concentrations of 3 mmol L^−1^ and 7 mmol L^−1^ respectively were used. The reaction rate of purpurogallin synthesis was maximum (2241.94 mg purpurogallin mg^−1^ CLEC h^−1^) at a residence time of 3.5 s, when 5 mmol L^−1^ pyrogallol was used as the substrate. The catalyst to product ratio calculated for the present biotransformation was 1:2241. The CLEC laccase had very high stability in reuse and even after 650 h of continuous use, the enzyme did not lose its activity. Copyright © 2006 Society of Chemical Industry