固定化N-乙酰鸟氨酸脱酰基酶拆分消旋蛋氨酸

Resolution of methionine by immobilized N-acetylornithine deacetylase

基因工程菌BL21/pET22b-argE可高效表达N-乙酰鸟氨酸脱酰基酶。将含酶细胞包埋于海藻酸钙凝胶中制成固定化细胞酶,用于消旋蛋氨酸的拆分,并将其拆分能力、拆分速度及操作稳定性与游离细胞酶相比较。结果表明：单批次转化固定化细胞酶的拆分能力和游离细胞酶相近,拆分速度较慢;但多批次转化的操作稳定性显著高于游离细胞酶。重复利用8次后的固定化细胞酶仍保有95%以上的酶活力,重复利用5次后的游离细胞酶活已降至20%左右。每克湿菌泥在游离和固定化条件下重复拆分产L-蛋氨酸的量分别为74.16mmol和241.93mmol。酶拆分液中的L-蛋氨酸经重结晶后光学纯度为98.3%。固定化细胞酶比游离细胞酶更具有工业化应用的潜质。

N-acetylornithine deacetylase was expressed by the genetic engineering strain BL21/pET22b-argE.Immobilized cell enzyme embedded in calcium alginate was used to split D,L-methionine.The ability and the speed to split methionine,and the operate stability were compared with free cell enzyme.The result indicated that the ability to split methionine of immobilized cell enzyme was equal but the speed was slower than free cell enzyme in single batch.But the operation stability was higher than that of repeat batches.Immobilized cell enzyme activity remained more than 95% after repeatedly used 8 times and free cell enzyme activity declined about to 20% after repeatedly used 5 times.The production of L-methionine with unit bacteria in free cells and immobilized cells were 74.16 mmol and 241.93 mmol,respectively.The optical purity of crystal L-methionine was 98.3% after recrystallization.Immobilized cell enzyme had more capability of industrial application than free cell enzyme.