中文摘要：

编码 synthase 是的 5-aminolevulinate (翼) 的新缝 A 基因克隆的 fromAgrobacterium radiobacter zju-0121.The 翼 synthase 催化 succinyl 辅酶 A (succinyl-CoA ) 和甘氨酸的 pyridoxal phosphate-dependentcondensation 生产带 A.radiobacter 缝的 ALA.Four 原生质标志基因被转变成不同 E.coli 种类。翼 synthase 和翼生产 werestudied.The 结果的表示上的基因、生理的因素的效果显示翼 synthase 和在不同表示系统的翼的生产的最后的细胞内部的活动大部分变化了。在他们之中，怀有表示原生质标志 pET28-A.R-hemA 的重新组合 E.coliBL21 (DE3 ) 是最合适的。效果 ofisopropyl-beta-D-thiogalactopyranoside (IPTG ) 增加时间， IPTG 集中，文化温度和翼生产上的先锋和葡萄糖的起始浓度是表示的 alsoevaluated.The 翼 synthase 说明了因为翼 synthase 的大约 23.7% 细胞内部的 solubleprotein.The 高比放射性是 13.8nmol-min ~(-1)centre dotmg~(-1)ofintracellular 可溶的蛋白质。在重新组合 E.coli 的批文化，细胞外的 ALAconcentration 到达了 0.9g 中心点 L~(-1) 。

英文摘要：

A new hemA gene encoding 5-aminolevulinate （ALA） synthase was cloned from Agrobacterium radiobacter zju-0121. The ALA synthase catalyzes the pyridoxal phosphate-dependent condensation of succinyl coenzyme A （succinyl-CoA） and glycine to produce ALA. Four plasmids carrying the A. radiobacter hemA gene were transformed into different E. coli strains. The effects of both genetic and physiological factors on the expression of ALA synthase and ALA production were studied. The results indicated that the final intracellular activity of ALA synthase and the production of ALA in different expression systems varied largely. Among them, the recombinant E. coli BL21 （DE3） harboring the expression plasmid pET28-A. R-hemA was the most suitable one. The effects of isopropyl-β-D-thiogalactopyranoside （IPTG） addition time, IPTG concentration, culture temperature and the initial concentration of precursors and glucose on the ALA production were also evaluated. The expressed ALA synthase accounted for about 23.7% of the intracellular soluble protein. The highest specific activity of ALA syn- thase was 13.8 nmol.min^-1.mg^-1 of intracellular soluble protein. In the batch culture of the recombinant E. coli, the extracellular ALA concentration reached 0.9g.L^-1.