对氨基苯甲酸(PABA)的生物合成及酶功能的相互影响

The Biosynthesis of p-Aminobenzoate And The Interdependence of Aminodeoxychorismate Synthase And Aminodeoxychorimate Lyase

由莽草酸经分枝酸进行的生物合成有五个反应途径 ,其中最复杂的是对氨基苯甲酸 (PABA)的合成 ,反应涉及到三个酶PabA、PabB和PabC。利用提纯的酶于实验里再现了生物体内的这一合成过程 ,在λ =2 65nm对酶的活性进行了连续的测定 ,经核磁共振确认了产物为PABA。在对底物作用中 ,PabB和PabC二聚体的形成对PABA的生物合成过程十分重要 ,它加速了PABA从PabB上的解离速度。当所加入的PabB和PabC的浓度比趋于 1:1时 ,PABA的生成速率趋于最大。

The biosynthesis beginning from shikimate and via chorimate have five different pathways.Among them the most complicated one is the synthesis of p aminobenzoate (PABA).Three enzymes,PabA,PabB and PabC,are involved in the synthesis .The assay experiment in vitro was done in Cary at λ=265 nm to determinate the activities of PabB and PabC continuously.It showed the dimer formed by PabB and PabC was highly important for the biosynthesis of PABA.The pyruvate lysised and the six carbon cycle aromatized by the aminodeoxy chorismate lyase accelerated the release of p-aminobenzoate from PabB and speeded up the metabolism,especially at their concentration rate tending to 1:1