In-silico and empirical site-directed substitutions of oxyanion Q114 of the wildtype T1 lipase with that of hydrophobic Leu and Met residues were carried out to afford the Q114L and Q114M lipases, respectively. Using the esterification production of menthyl butyrate as a reaction model, evaluation on the catalytic efficiency of the three lipases was performed. It was found that Leu evidently improved the catalytic activity of the Q114L lipase, achieving the highest conversions of menthyl butyrate under varying experimental conditions that may be attributable to its lower total energy when compared with both the T1 and Q114M lipases. The diminishing catalytic activity of T1 lipase observable following substitution with Met (Q114M lipase) may be due to formation of three additional cavities within the vicinity of the mutation, lesser density of the protein core and susceptibility to high temperature, particularly under prolonged reaction time. Therefore, it can be concluded that the substitution of Leu into the oxyanion-114 had rendered favorable structural changes that enhanced the catalytic activity of the T1 lipase, envisaging that such approach may also be of applied value for improving the catalytic activity of other bacterial lipases within the I.5 family.