RESUMEN

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, a w 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.