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本文报道用含ｔｙｒＢ基因（在大肠杆菌中编码芳香族氨基酸转氨酶）的质粒ｐＫＢ７转化不同的突主菌，筛选出ＣＴＢ２菌（ｐＫＢ７转化ＪＭ１０７得到）表达的芳香族氨基酸转氨酶活力最高。进一步研究证明ＣＴＢ２菌在菌浓度为２０ｍｇ／ｍｌ，温度３０℃，反就６０分钟．能催化苯丙酮酸加氨生成大量的Ｌ－苯内氮酸，而没有付产物酪氨酸生戊。以从ＣＴＢ２菌中提取纯化出的质粒为模板，经ＰＣＲ扩增反应可以得到约长１．２ｋｂ的ｔｙｒＢ基因片段，ＳＤＳ－聚丙烯酰胺凝胶电泳实验表明ＣＴＢ２菌可溶性蛋白在分子量约４００００，有一条明显加深的蛋白区带，这与理论估算的芳香族氨基酸转氨酶的分子量４３０００基本一致。而ＪＭ１０７和含ｐＫＫ２３３－２空质粒的ＪＭ１０７在该位点的区带则没有加深，该加深区带的蛋白含量占到总溶性蛋白的２０％左右。
In this paper, we report the transformation of different mutant hosts with plasmid pKB7 containing the tyrB gene (encoding aromatic amino acid transaminase in Escherichia coli). The amino acid transaminases with the highest expression of CTB2 (pKB7 transformed JM107) were obtained. Further study proved that CTB2 bacteria in the bacteria concentration of 20mg / ml, temperature 30 ℃, anti-60 minutes. Benzene pyruvate catalyst can catalyze the formation of a large number of L-Benzene nitric acid, but did not pay the product tyrosine penta. The tyrB gene fragment of about 1.2kb was obtained by PCR amplification of the purified plasmid from CTB2 bacteria. SDS-polyacrylamide gel electrophoresis showed that the soluble protein of CTB2 strain had a molecular weight of about 40,000 A significantly deepened protein band, which is basically consistent with the theoretical molecular weight of 43000 aromatic amino acid transaminase. While JM107 and JM107 containing pKK233-2 empty plasmid did not deepen the band at this locus, and the protein content of the deepening zone accounted for about 20% of the total soluble protein.