Artículos de revistas
Kinetic properties and enantioselectivity of the lipases produced by four Aspergillus species
Food Biotechnology. Taylor & Francis Inc, v. 19, n. 3, n. 183, n. 192, 2005.
Four high lipase-producing Aspergillus species, selected in our laboratory, were compared in terms of their stability and reactivity for enantioselective esterification between (R, S)-2-octanol with octanoic acid in n-hexane. We determined the pH and temperature reactions dependences of lipases activities, and we found that these enzymes exhibited various pH sensitivities. The optimum pH observed for Aspergillus terreus lipase was 5.5, for A. niger and A. oryzae lipases in the range of 6.0 to 6.5 and pH 7.0 for A. flan us lipase. Good stability was observed at pH ranging from 5.0 to 8.5 after 24 hours at 40 degrees C, and the optimum activity was observed at 35-40 degrees C for all lipases tested. The lipases from A. terreus and A. niger were highly thermostable, retaining 60% and 50% activity at 60 C after 1 hour, respectively. The lipases from A. niger and A. terreus lipases provided the best results in terms of enantioselectivity (E) in the esterification of (R, S)-2-octanol with octanoic acid in n-hexane (E = 4.9 and E = 4.5, respectively). These properties make these lipases good candidates for biocatalysis in organic media.193183192