固定化D-氨基酸氧化酶催化DL-氨基酸去消旋化制备非天然L-氨基酸

在过氧化氢酶和氧气存在下,固定化D-氨基酸氧化酶(D-AAO)对映选择性催化DL-氨基酸中的D-对映体氧化脱氨为相应酮酸,L-对映体保留.研究了D-AAO的底物特异性并对反应条件进行了优化.结果表明:D-AAO具有较宽的底物谱,能够催化疏水性α-氨基酸的D-对映体氧化脱氨.在最优反应条件下,D-AAO催化DL-2-氨基丁酸、DL-2-氨基戊酸去消旋化,L-2-氨基丁酸、L-2-氨基戊酸的收率分别为48%和47%,ee分别为99.5%和99.8%.进一步地利用Pd-C/HCOONH4催化氧化脱氨过程中产生的亚氨基酸原位还原,有效提高了L-2-氨基丁酸、L-2-氨基戊酸的收率并保持高的光学纯度.

Preparation of Non-natural L Amino Acids via Deracemization of DL-Amino Acids Catalyzed by Immobilized D-amino Acid Oxidase

The D-enantiomer of DL-amino acid is oxidative deaminated enantioselectively into the corresponding oxo acid by immobilized D-amino acid oxidase(D-AAO) in the presence of catalase and oxygen,and the L-enantiomer is retained.The substrate specificity of D-AAO was studied and the reaction conditions were optimized.The results showed that D-AAO has a broader substrate spectrum and is capable of catalyzing the oxidative deaminzation of hydrophobic D-α-amino acids.Under the optimal conditions,L-2-aminobutyric acid and L-2-aminovaleric acid were obtained in 48% and 47% yield,99.5% and 99.8% ee respectively.Furthemore,the yields of L-2-aminobutyric acid and L-2-aminovaleric acid were improved and their optically purity were retained through in-situ reduction of imine acids produced during the oxidative deaminization by Pd-C/HCOONH4.