Biomolecular Chemical Simulations toward Elucidation of the Enantioselectivity and Reactivity of Lipases in Organic Synthesis

We are presently continuing to perform biomolecular chemical simulations for Burkholderia cepacia lipase (BCL) and Candida antarctica lipase typeB (CALB) to predict their enantioselectivity and reactivity toward various organic compounds. Here, we describe molecular dynamics (MD) and fragment molecular orbital (FMO) calculations on the complexes of CALB with primary and secondary alcohol esters. For esters with high enantioselectivity, the fast-reacting enantiomer of esters is located near the active site of CALB, whereas the slow-reacting enantiomer of esters moves away from the active site of CALB. On the other hand, for the esters with low enantioselectivity, we found that both (R)and (S)-enantiomers of esters remain the active site of CALB. The FMO computations indicate that for the esters with high enantioselectivity, each fast-reacting enantiomer shows strong interactions with some particular amino acid residues, including Thr40, whereas for the esters with low enantioselectivity, both (R)and (S)-enantiomers interact with identical amino acid residues including Thr40. It is predictable that Thr40 in CALB plays an important role in the chiral recognition of enantiomers through lipase-catalyzed biotransformations.