一、概况青霉素G及V、头孢菌素C、头霉素C生物合成的初始阶段都一样,这些化合物的生物合成全过程见图1。Ingolia及Queener(1988)提出了生物合成基因的分类命名、青霉素和头孢菌素相同的生物合成基因,命名为Pcb(青霉素/头孢菌素生物合成),只限于青霉素或头孢菌素的,分别命名为pen及cef。L-α-氨基己二酸、L-半胱氨酸及L-缬氨酸的酶缩合,伴同发生缬氨酸的异构化而成为D型。在半纯化的酶提取液中,曾观察 First, an overview of penicillin G and V, cephalosporin C, cephalosporin C biosynthesis of the initial stage are the same, the biosynthesis of these compounds the entire process shown in Figure 1. Ingolia and Queener (1988) proposed the taxonomic nomenclature of biosynthetic genes, the same biosynthetic genes for penicillin and cephalosporin, named Pcb (penicillin / cephalosporin biosynthesis), limited to penicillins or cephalosporins, each named For pen and cef. Enzymatic condensation of L-α-aminoadipic acid, L-cysteine ​​and L-valine is accompanied by D-isomerization of valine. In the semi-purified enzyme extract, it has been observed