Carica papaya lipase: a versatile enantioselectivity biocatalyst

The papaya lipase stored in the crude papain from spay-dried latex of Carica papaya has been discovered as a versatile enantioselectivity biocatalyst to obtain chiral acids by using hydrolytic resolution of their racemic esters. With adopting the enzyme screening, purification, medium engineering and substrate engineering tactics can effectively improve the ability of lipase- catalyzed hydrolysis of (R,S)-naproxen ester. By employing partially purified lipase or an appropriate organo-soluble base (ex: Triethylamine) addition in water-saturated isooctane, both have superior enhancement of lipase activity or enantioselectivity. In addition, it was also found that initial rate enhancement for (S)-ester displayed as increasing the inductive parameter (electron-withdraw capability), therefore it further implies the acylaction step must be the rate- limiting step during enzyme-catalyzed process. Besides, a novel means of applying substrate- assisted catalysis demonstrated the proton shuttle device acts as an effective tool for improving the lipase activity by forming an extra intra-molecular hydrogen bond (11.5~11.9 KJ/mol) in the transition state.