The gene epsN of Bacillus subtilis 168 was cloned and overexpressed in Escherichia coli. Purified recombinant EpsN is shown to be a pyridoxal 5′-phosphate (PLP)-dependent aminotransferase by absorption spectroscopy, l-cycloserine inhibition and reverse phase HPLC studies. EpsN catalyzes the conversion of UDP-2,6-dideoxy 2-acetamido 4-keto glucose to UDP-2,6-dideoxy 2-acetamido 4-amino glucose. Lys190 was found by sequence comparison and site-directed mutagenesis to form Schiff base with PLP. Mutagenesis studies showed that, in addition to Lys190, Ser185, Glu164, Gly58 and Thr59 are essential for aminotransferase activity.

中文翻译：

---

枯草芽孢杆菌168的EpsN在体外具有UDP-2,6- dideoxy 2-acetamido 4-keto葡萄糖氨基转移酶活性

在大肠杆菌中克隆了枯草芽孢杆菌168基因epsN。通过吸收光谱，1-环丝氨酸抑制和反相HPLC研究，纯化的重组EpsN显示为吡be醛5'-磷酸（PLP）依赖性氨基转移酶。EpsN催化UDP-2,6-二脱氧2-乙酰氨基4-酮葡萄糖向UDP-2,6-二脱氧2-乙酰氨基4-氨基葡萄糖的转化。通过序列比较和定点诱变发现Lys190与PLP形成席夫碱。诱变研究表明，除了Lys190外，Ser185，Glu164，Gly58和Thr59对于氨基转移酶活性也是必不可少的。