The yield is defined as the proportion of rac-BMBA converted into BAP (%). The maximum theoretical yield for the kinetic resolution is thus 50 %. The specific activity is defined as the number of µmol of 4'-bromacetophenone formed per minute per mg of immobilized enzymes and evaluated by Eq. 2, where L is the immobilized enzyme loading (determined by mass balance via the Bradford method (mg)) and, t is the reaction time (min).