Alvarez-Macarie_2000_J.Mol.Catal.B.Enzym_10_377

Abstract: The newly characterized esterase from Bacillus licheniformis was used for ethyl ester synthesis in n-heptane by direct esterification with fatty acids of different chain lengths. The highest reaction rates and yields were obtained with caproic (C6) and caprylic (C8) acids reflecting the enzyme specificity for mid-chain length fatty acids. The rate of ethyl caproate formation increased linearly with the enzyme concentration in the range 040 mg/ml. The enzyme displayed maximum activity with 0.1% (v/v) addition of water. The initial reaction rate was maximal at 67C but the highest yield (95%) was obtained at 45C. Kinetic parameters were determined for caproic acid: KM of 38.4 mM and VM of 8.3 micromol/min/ml (at 0.25 M ethanol), and for ethanol KM of 12.3 mM and VM of 1.3 micromol/min/ml (at 0.25 M caproic acid). The highest activities and yields were observed for solvents having log P=3.2. The enzyme was used three times without activity loss.