Kimura K, Sasakawa T
J Biochem. 1975 Aug;78(2):381-90. doi: 10.1093/oxfordjournals.jbchem.a130918.
Non-enzymatic formation of dipicolinic acid (DPA) from diketopimelic acid and ammonia was clearly demonstrated using a new method for DPA analysis. The reaction rates of DPA formation were almost the same under aerobic and anaerobic conditions. Nearly equimolecular quantities of DPA and tetrahydrodipicolinic acid were detected in spontaneous reaction mixture. The spontaneous reaction seemed to be due to dismutation of dihydrodipicolinic acid, resulting in DPA and tetrahydrodipicolinic acid. The apparent optimum pH of the spontaneous reaction was 8.2 and the maximal rate of DPA formation was observed with a 1 : 4 molar ratio of diketopimelic acid to ammonia. The rate of the spontaneous reaction was stimulated by ferrous sulfate, FMN, and riboflavin. Dihydrodipicolinate reductase catalyzes the reduction of dihydrodipicolinate, prepared from pyruvate and aspartic beta-semialdehyde, with NADPH as reductant. The reductase was isolated from Bacillus subtilis, and found to stimulate DPA formation from diketopimelic acid and ammonia. The enzymatic DPA formation was absolutely dependent on oxygen, and optimum pH was 6.4. The catalytic action of the enzyme was similar to that of the oxidase. Possible mechanisms of DPA formation from diketopimelic acid and ammonia are proposed.
使用一种新的二吡啶甲酸（DPA）分析方法，明确证实了由二酮哌嗪酸和氨非酶促形成DPA的过程。在有氧和无氧条件下，DPA形成的反应速率几乎相同。在自发反应混合物中检测到了几乎等分子数量的DPA和四氢二吡啶甲酸。自发反应似乎是由于二氢二吡啶甲酸的歧化作用，生成了DPA和四氢二吡啶甲酸。自发反应的表观最佳pH值为8.2，当二酮哌嗪酸与氨的摩尔比为1:4时，观察到DPA形成的最大速率。硫酸亚铁、黄素单核苷酸（FMN）和核黄素能促进自发反应的速率。二氢二吡啶甲酸还原酶催化由丙酮酸和β-天冬氨酸半醛制备的二氢二吡啶甲酸的还原反应，以烟酰胺腺嘌呤二核苷酸磷酸（NADPH）作为还原剂。该还原酶从枯草芽孢杆菌中分离得到，并发现它能促进由二酮哌嗪酸和氨形成DPA。酶促形成DPA绝对依赖于氧气，最佳pH值为6.4。该酶的催化作用与氧化酶相似。提出了由二酮哌嗪酸和氨形成DPA的可能机制。
