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Enhancement of lipase activity in non-aqueous media upon immobilization on multi-walled carbon nanotubes.

Shah S, Solanki K, Gupta MN - Chem Cent J (2007)

Bottom Line: Lipases from Candida rugosa (CRL) were found to be adsorbed on the multiwalled carbon nanotubes with very high retention of their biological activity (97%).The immobilized enzyme was found to give 64% conversion over 24 h (as opposed to 14% with free enzyme) in the formation of butylbutyrate in nearly anhydrous hexane.While free CRL gave only 5% conversion after 36 h, the immobilized enzyme resulted in 37% conversion with > 99% enantiomeric excess.

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Affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India. s_shahvns@rediffmail.com

ABSTRACT

Background: Immobilization of biologically active proteins on nanosized surfaces is a key process in bionanofabrication. Carbon nanotubes with their high surface areas, as well as useful electronic, thermal and mechanical properties, constitute important building blocks in the fabrication of novel functional materials.

Results: Lipases from Candida rugosa (CRL) were found to be adsorbed on the multiwalled carbon nanotubes with very high retention of their biological activity (97%). The immobilized biocatalyst showed 2.2- and 14-fold increases in the initial rates of transesterification activity in nearly anhydrous hexane and water immiscible ionic liquid [Bmim] [PF6] respectively, as compared to the lyophilized powdered enzyme. It is presumed that the interaction with the hydrophobic surface of the nanotubes resulted in conformational changes leading to the 'open lid' structure of CRL. The immobilized enzyme was found to give 64% conversion over 24 h (as opposed to 14% with free enzyme) in the formation of butylbutyrate in nearly anhydrous hexane. Similarly, with ionic liquid [Bmim] [PF6], the immobilized enzyme allowed 71% conversion as compared to 16% with the free enzyme. The immobilized lipase also showed high enantioselectivity as determined by kinetic resolution of (+/-) 1-phenylethanol in [Bmim] [PF6]. While free CRL gave only 5% conversion after 36 h, the immobilized enzyme resulted in 37% conversion with > 99% enantiomeric excess. TEM studies on the immobilized biocatalyst showed that the enzyme is attached to the multiwalled nanotubes.

Conclusion: Successful immobilization of enzymes on nanosized carriers could pave the way for reduced reactor volumes required for biotransformations, as well as having a use in the construction of miniaturized biosensensor devices.

No MeSH data available.


Transesterification of ethyl butyrate with butanol in hexane. Each point represents the outcome of a pair of readings.
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Figure 1: Transesterification of ethyl butyrate with butanol in hexane. Each point represents the outcome of a pair of readings.

Mentions: As the lipase immobilized on MWNT showed higher initial transesterification rates in hexane, its utility in the biotransformation was evaluated by the conversion of ethyl butyrate to butyl butyrate over larger reaction periods. Figure 1 shows that CRL immobilized on MWNT gave much better conversion rates. The immobilized enzyme gave 64% conversion after 24 h, whereas the free enzyme gave 14% conversion after the same reaction period. Even in [Bmim] [PF6] the immobilized enzyme was a far better catalyst (Figure 2). The immobilized enzyme showed 71% conversion, whilst the free enzyme gave 16% conversion after 24 h. Again, the enzyme immobilized in the absence of BSA performed better. In a control where only MWNTs without enzyme were added, no transesterification activity could be obtained either in hexane or in the ionic liquid.


Enhancement of lipase activity in non-aqueous media upon immobilization on multi-walled carbon nanotubes.

Shah S, Solanki K, Gupta MN - Chem Cent J (2007)

Transesterification of ethyl butyrate with butanol in hexane. Each point represents the outcome of a pair of readings.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211749&req=5

Figure 1: Transesterification of ethyl butyrate with butanol in hexane. Each point represents the outcome of a pair of readings.
Mentions: As the lipase immobilized on MWNT showed higher initial transesterification rates in hexane, its utility in the biotransformation was evaluated by the conversion of ethyl butyrate to butyl butyrate over larger reaction periods. Figure 1 shows that CRL immobilized on MWNT gave much better conversion rates. The immobilized enzyme gave 64% conversion after 24 h, whereas the free enzyme gave 14% conversion after the same reaction period. Even in [Bmim] [PF6] the immobilized enzyme was a far better catalyst (Figure 2). The immobilized enzyme showed 71% conversion, whilst the free enzyme gave 16% conversion after 24 h. Again, the enzyme immobilized in the absence of BSA performed better. In a control where only MWNTs without enzyme were added, no transesterification activity could be obtained either in hexane or in the ionic liquid.

Bottom Line: Lipases from Candida rugosa (CRL) were found to be adsorbed on the multiwalled carbon nanotubes with very high retention of their biological activity (97%).The immobilized enzyme was found to give 64% conversion over 24 h (as opposed to 14% with free enzyme) in the formation of butylbutyrate in nearly anhydrous hexane.While free CRL gave only 5% conversion after 36 h, the immobilized enzyme resulted in 37% conversion with > 99% enantiomeric excess.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India. s_shahvns@rediffmail.com

ABSTRACT

Background: Immobilization of biologically active proteins on nanosized surfaces is a key process in bionanofabrication. Carbon nanotubes with their high surface areas, as well as useful electronic, thermal and mechanical properties, constitute important building blocks in the fabrication of novel functional materials.

Results: Lipases from Candida rugosa (CRL) were found to be adsorbed on the multiwalled carbon nanotubes with very high retention of their biological activity (97%). The immobilized biocatalyst showed 2.2- and 14-fold increases in the initial rates of transesterification activity in nearly anhydrous hexane and water immiscible ionic liquid [Bmim] [PF6] respectively, as compared to the lyophilized powdered enzyme. It is presumed that the interaction with the hydrophobic surface of the nanotubes resulted in conformational changes leading to the 'open lid' structure of CRL. The immobilized enzyme was found to give 64% conversion over 24 h (as opposed to 14% with free enzyme) in the formation of butylbutyrate in nearly anhydrous hexane. Similarly, with ionic liquid [Bmim] [PF6], the immobilized enzyme allowed 71% conversion as compared to 16% with the free enzyme. The immobilized lipase also showed high enantioselectivity as determined by kinetic resolution of (+/-) 1-phenylethanol in [Bmim] [PF6]. While free CRL gave only 5% conversion after 36 h, the immobilized enzyme resulted in 37% conversion with > 99% enantiomeric excess. TEM studies on the immobilized biocatalyst showed that the enzyme is attached to the multiwalled nanotubes.

Conclusion: Successful immobilization of enzymes on nanosized carriers could pave the way for reduced reactor volumes required for biotransformations, as well as having a use in the construction of miniaturized biosensensor devices.

No MeSH data available.