The n - terminus truncated mutant can not form tight dimeric and tetrameric structure , and leads to the destruction of the quaternary structure , which is quite the contrary to wild type arog . these data indicate that n - terminus of arog is not only involved in the feedback inhibition , but also plays a role in the formation of stable dimer which is an essential structure for its enzymatic activity . according to the 3d structure , " d2 " symmetry of arog , to which contributed by leu 16 , trp215 and his217 , is essential for the feedback inhibition 对“ dz ”对称性相关的氨基酸leul6 、 trpz15和hisz17进行点突变和双突变研究结果表明: l )在1mm苯丙氨酸的存在下， leul6ala 、 trpz15ala和hisz17ala能解除35一70 %的反馈抑制， t印2巧ala的比活降低65 %以上，其余两者的比活与野生型相近; 2 )在lmm苯丙氨酸的存在下，导入双点突变trpz1sai洲isz17ala和leul6hi撇isz17leu后能够完全解除arog的反馈抑制，同时保持与野生型相当的比活。
