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Enzyme Research
Volume 2013, Article ID 928913, 11 pages
http://dx.doi.org/10.1155/2013/928913
Research Article

Immobilization and Biochemical Properties of the Enantioselective Recombinant NStcI Esterase of Aspergillus nidulans

1Department of Food Science and Biotechnology, Faculty of Chemistry, National Autonomous University of Mexico (UNAM), 04510 Mexico City, DF, Mexico
2Department of Biochemistry, Faculty of Medicine, UNAM, 04510 Mexico City, DF, Mexico

Received 29 January 2013; Revised 11 March 2013; Accepted 11 March 2013

Academic Editor: Joaquim Cabral

Copyright © 2013 Carolina Peña-Montes et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The recombinant NStcI A. nidulans esterase was adsorbed on Accurel MP1000, where protein yield and immobilization efficiency were 42.48% and 81.94%, respectively. Storage stability test at 4°C and RT showed 100% of residual activity after 40 days at both temperatures. The biocatalyst retains more than 70% of its initial activity after 3 cycles of repeated use. Biochemical properties of this new biocatalyst were obtained. Maximum activity was achieved at pH 11 and 30°C, while the best stability was observed with the pH between 9 and 11 at 40°C. NStcI thermostability was increased after immobilization, as it retained 47.5% of its initial activity after 1 h at 60°C, while the free enzyme under the same conditions displayed no activity. NStcI preserved 70% of its initial activity in 100% hexane after 72 h. Enzymatic kinetic resolution of (R,S)-1-phenylethanol was chosen as model reaction, using vinyl acetate as acyl donor. After optimization of reaction parameters, the highest possible conversion (42%) was reached at 37°C, of 0.07, and 120 h of bioconversion in hexane with an enantiomeric excess of 71.7%. NStcI has selectivity for (R)-enantiomer. The obtained E value (31.3) is in the range considered useful to resolve enantiomeric mixtures.