Chang-Han Tsai

Bio: Chang-Han Tsai is an academic researcher from National Chung Hsing University. The author has contributed to research in topics: Dipeptide & Lipase. The author has an hindex of 2, co-authored 2 publications receiving 10 citations.

Formation of amide bond catalyzed by lipase in aqueous phase for peptide synthesis

Abstract: A dipeptide N -acetyl- l -phenylalanyl- l -tyrosinamide ( N -Ac-Phe-Tyr-NH 2 ), with angiotensin I converting enzyme (ACE) inhibitor activity, was synthesized via porcine pancreatic lipase catalyzed amidation of N -acetyl-phenylalanine ethyl ester with l -tyrosinamide in an aqueous phase. Response surface methodology was employed to evaluate the effects of synthesis parameters. The optimum synthesis conditions obtained an 84.45% yield of N -Ac-Phe-Tyr-NH 2 with a reaction time of 3.8 min, a temperature of 20.9 °C, an enzyme amount of 6.5 U, and a substrate molar ratio of 2.5:1 (Tyr:Phe). The kinetics of lipase and α-chymotrypsin catalyzed amidation was compared using the Ping-Pong mechanism. The lipase showed a lower apparent kinetic constant than α-chymotrypsin indicating that the acyl lipase intermediate had a higher affinity toward tyrosinamide in the amidation. In addition, because the lipase can avoid the secondary hydrolysis of synthesized peptide, it is expected to be an effective method for obtaining a good yield of dipeptide.

Lipase-Mediated Amidation of Anilines with 1,3-Diketones via C–C Bond Cleavage

Abstract: In this work, an efficient and green lipase-mediated technique has been mined for the amidation of anilines with 1,3-diketones via C–C bond cleavage. Under the optimal conditions, high yields (64.3%–96.2%) could be obtained when Novozym 435 was used as the catalyst. Furthermore, Novozym 435 exhibited a satisfying reusability and more than 80% of yield can be obtained after seven cycles. This work provides a more rapid and mild strategy for amide synthesis with high yield and expands the application of enzyme in organic synthesis.

Biosynthesis of Alanyl-Histidine Dipeptide Catalyzed by Papain Immobilized on Magnetic Nanocrystalline Cellulose in Deep Eutectic Solvents.

Abstract: Papain (PA) immobilized onto magnetic nanocrystalline cellulose (PA@MNCC) was successfully fabricated and adopted as an efficient biocatalyst for the synthesis of N-(benzyloxycarbonyl)-alanyl-histidine (Z-Ala-His) dipeptide. Introducing deep eutectic solvents (DESs) as reaction media promoted the synthesis of the Z-Ala-His dipeptide. The effects of reaction conditions on the yield of papain catalytic Z-Ala-His were systematically investigated with the highest yield of 68.4%, which was higher than free papain (63.3%). Besides, this novel PA@MNCC composite can be easily recycled from the reaction system by magnetic forces. In a word, the PA@MNCC composite exhibited great potential for efficient biosynthesis of dipeptide in DESs.