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P. V. Nurullina, L. V. Perminova, G. A. Kovalenko
Catalytic
properties of rPichia/lip lipase adsorbed on carbon nanotubes in the
reaction of low-temperature synthesis of esters
Abstract
Immobilization
of recombinant rPichia/lip lipase was performed by adsorption of this
enzyme on aggregated carbon nanotubes, unmodified (CNT) or nitrogen-doped
(N-CNT). Heterogeneous biocatalysts such prepared were investigated in the
reaction of synthesis of esters proceeding in organic solvents under ambient
condition. The texture and morphology of unmodified CNTs, as well as nitrogen
content of doped N-CNTs were found to influence the catalytic properties of the
adsorbed lipase such as enzyme activity, specificity and stability. Activity of
the biocatalysts and specific activity of the immobilized lipase increased by
1.5–1.6 times as the content of nitrogen inside CNTs increased (from 2 to 5 wt%
N). Study on the immobilized lipase specificity in the esterification of
saturated fatty acids (heptanoic, stearic) with aliphatic alcohols (n-butanol,
n-hexadecanol) showered, that the maximum reaction rate was observed in
the synthesis of n-butyl heptanoate. In the batch etherification
process, the prepared biocatalysts had a high operational stability and
retained at least 80% of the initial activity for 36 reaction cycles (720 h).
Key words: lipase, adsorption, carbon nanotubes, synthesis of esters.
Copyright (C) Chemistry Dept., Moscow State University, 2002
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