Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

In this study, we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). First, adenylate cyclase from Escherichia coli MG1655 (EAC) and Bordetella Pertussis (BAC) were expressed in E. coli BL21 (DE3) and comparatively analyzed for their activities. As a result, EAC from E. coli MG1655 exhibited a higher activity. However, amount of EAC were obtained in an insoluble form. Therefore, we expressed the first 446 amino acids of EAC (EAC446) to avoid the inclusion body. The effects of induction temperature, incubation time, and incubation pH were further evaluated to improve the expression of EAC446. Subsequently, the reaction process for the production of cAMP with ATP as a starting material was investigated. As none of cAMP was detected in the whole-cell based biocatalytic process, the reaction catalyzed by the crude enzyme was determined for cAMP production. What's more, the reaction temperature, reaction pH, metal ion additives and substrate concentration was optimized, and the maximum cAMP production of 18.45 g·L⁻¹ was achieved with a yield of 95.4% after bioconversion of 6 h.