کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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683115 | 888995 | 2010 | 6 صفحه PDF | دانلود رایگان |
Cross-linked enzyme aggregates (CLEAs) are reported for the first time for a recombinant acetyl xylan esterase (AXE) from Bacillus pumilus. With this enzyme, CLEAs production was most effective using 3.2 M (80%-saturation) ammonium sulfate, followed by cross-linking for 3 h with 1% (v/v) glutaraldehyde. Particle size was a key determinant of the CLEAs activity. The usual method for generating particles, by short-time vortexing was highly inefficient in terms of enzyme activity yields. In contrast, the use of long-time vortexing increased activity recovery, and a novel approach consisting in the utilization of a commercial mechanical cell disruptor which is based on a reciprocating movement recovered all the enzyme activity in few seconds. In the CLEAs thus produced, the enzyme was much more resistant to shear, heat and extreme pH values than the soluble enzyme. The CLEAs were highly effective in transforming fully 7-amino cephalosporanic acid and cephalosporin C into their corresponding desacetyl derivatives, which are important advanced intermediates in the production of semisynthetic β-lactam antibiotics. The operational stability of such CLEAs was remarkable, with a half life of 45 cycles. Therefore, the new methodology used here should decrease the industrial cost of the CLEAs, both in terms of biocatalyst production and reusability.
Journal: Bioresource Technology - Volume 101, Issue 1, January 2010, Pages 331–336