The proposed mechanism of the catalytic cycle of CAL-B-catalysed transesterification of DMFDCA with α,ω-ALD, and DLD based on the mechanism described by Puskas and Garcia, Histidine (His224), and Aspartic acid (Asp187), arranged in a specific spatial orientation within the enzyme's active site. Another important structural feature of the active site of CAL-B is the oxyanion hole, which helps facilitate its catalytic activity. The oxyanion hole is a pocket-like structure located above the catalytic triad that stabilizes the negative charge that develops on the carbonyl oxygen of the substrate during the reaction by using three hydrogen bonds. One bond is provided by glutamine (Gln106), and two are provided by threonine (Thr40).