Enhanced catalytic stability and reusability of nitrilase encapsulated in ethyleneamine-mediated biosilica for regioselective hydrolysis of 1-cyanocycloalkaneacetonitrile.
Int J Biol Macromol
; 130: 117-124, 2019 Jun 01.
Article
em En
| MEDLINE
| ID: mdl-30807797
ABSTRACT
Nitrilase-catalyzed regioselective hydrolysis of 1-cyanocyclohexaneacetonitrile (1-CHAN) is a green and efficient approach for the preparation of 1-cyanocyclohexaneacetic acid (1-CHAA), a key precursor for the synthesis of gabapentin. Here, a mesoporous biosilica particles prepared by the ethyleneamine-mediated silicification have been used as carrier for the encapsulation of nitrilase from Acidovorax facilis (NitA). The silica-encapsulated NitA (NitA@silica) with triethylenetetramine as an initiator showed the highest immobilization efficiency (98.3%) and specific activity (672.6â¯U/g). Both free and encapsulated NitA were optimally active at 40⯰C and pHâ¯7.0, however, the encapsulated enzyme exhibited wider optimum temperature range, and enhanced thermal stability compared with the free enzyme. The kinetic parameters Km and Vmax for free and encapsulated NitA were calculated to be 141â¯mM and 9.97â¯mMâ¯min-1, and 280â¯mM and 9.02â¯mMâ¯min-1, respectively. The encapsulated NitA showed good reusability and retained about 94.2% of its initial activity even after 16â¯cycles of reaction. Also, the storage experiments revealed high activity maintenance of encapsulated NitA after 17-day storage at 4⯰C. A preparative scale regioselective hydrolysis of 1-CHAN to 1-CHAA with encapsulated NitA as biocatalyst was carried out in a 2â¯L stirred bioreactor. The concentration of 1-CHAA reached 152â¯g/L after 8â¯h reaction and the conversion was 90.9%. These results showed that the encapsulation of NitA in ethyleneamine-mediated biosilica is an efficient and simple way for preparation of stable nitrilase and have a great potential for application in enzymatic production of carboxylic acids.
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MEDLINE
Assunto principal:
Acetonitrilas
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Trientina
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Cicloexanos
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Biocatálise
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Aminoidrolases
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Nitrilas
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article