Asymmetric Synthesis ofL-α-Methylcysteine with the Amidase fromXanthobacter flavus NR303
作者:Atsushi Inoue、Hidenobu Komeda、Yasuhisa Asano
DOI:10.1002/adsc.200505028
日期:2005.6
An amidase acting on d, l-α-methylcysteinamide was purified from Xanthobacter flavus NR303. The enzyme acted L-stereoselectively on d,l-α-methylcysteinamide to yield L-α-methylcysteine. Based on the N-terminal amino acid sequence of the amidase, the gene encoding the enzyme was cloned from the genomic DNA of X. flavus and sequenced. Analysis of 4840 bp of the genomic DNA revealed the presence of an
从黄细菌黄单胞菌NR303中纯化作用于d,1-α-甲基半胱氨酰胺的酰胺酶。该酶对d,1-α-甲基半胱氨酸酰胺具有L-立体选择性作用,产生L-α-甲基半胱氨酸。根据酰胺酶的N端氨基酸序列,从黄萎病菌的基因组DNA中克隆出编码该酶的基因并进行测序。对4840 bp基因组DNA的分析显示,存在编码酰胺酶的开放阅读框(mcaA)。该酶由355个氨基酸残基(分子量38555 Da)组成。大肠杆菌转化体的完整细胞可用于外消旋α-甲基半胱氨酸酰胺的L-立体选择性水解。在Mn 2+存在下被活化,在pH 7.0和55°C下具有最大活性。的大肠杆菌转化体催化的从d L-α甲基半胱氨酸,L-α-methylcysteinamide的在80%的具有高光学纯度(> 98%ee)的产率合成。