Hu C Y, Sprinson D B
J Bacteriol. 1977 Jan;129(1):177-83. doi: 10.1128/jb.129.1.177-183.1977.
Tyrosine-inhibitable 3-deoxy-D-arabinoheptulosonic acid-7-phosphate (DAHP) synthase was purified to homogeneity without significant loss of sensitivity to inhibition by tyrosine from an operator-constitutive strain (tyrOc) of Salmonella. The enzyme had an apparent molecular weight of 76,000 by gel filtration and a subunit molecular weight of 40,000 by sodium dodecyl sulfate-gel electrophoresis and by reaction with dimethyl suberimidate. It had an isoelectric point of 4.68. Inhibition by L-tyrosine showed a Hill coefficient of 1.8 at pH 7.0, suggesting cooperative interaction between tyrosine-binding sites, and was competitive with phosphoenol pyruvate and noncompetitive with erythrose-4-phosphate.
酪氨酸可抑制的3-脱氧-D-阿拉伯庚酮糖酸-7-磷酸(DAHP)合酶从沙门氏菌的一个操纵子组成型菌株(tyrOc)中纯化至同质,且对酪氨酸抑制的敏感性没有显著损失。通过凝胶过滤,该酶的表观分子量为76,000,通过十二烷基硫酸钠-凝胶电泳和与辛二酸二甲酯反应,其亚基分子量为40,000。其等电点为4.68。L-酪氨酸的抑制在pH 7.0时显示出1.8的希尔系数,表明酪氨酸结合位点之间存在协同相互作用,并且与磷酸烯醇丙酮酸竞争,与4-磷酸赤藓糖非竞争。