Cobamamide

This work explores Cu-modified B₁₂N₁₂ and Al₁₂N₁₂ nanocages for cadaverine diamine (Cad) detection using advanced density functional theory (DFT) calculations. The study found that Cu modification altered the geometry of the nanocages, increased the dipole moment, reduced the energy gap, and enhanced the reactivity. While pristine B₁₂N₁₂ and Al₁₂N₁₂ were not sensitive to Cad, the modified Cu(b₆₄)B₁₂N₁₂ and Cu(b₆₆)Al₁₂N₁₂ nanocages showed significantly higher electronic sensitivity (Δgap = 39.8% and 35.6%, respectively), surpassing the literature data. However, molecular dynamics (MD) revealed that the Cu(b₆₆)Al₁₂N₁₂ nanocage is not stable in the long term, since the nanocage changes configuration to Cu(b₆₄)Al₁₂N₁₂, which is less sensitive and has an even longer recovery time for Cad sensing. Adsorption energy analysis (E_ads) showed a strong interaction of Cad/nanocages, while charge analysis suggested that the nanocages act as Lewis acids, accepting electrons from Cad. UV-vis spectra confirmed that Cu(b₆₄)B₁₂N₁₂ responds optically to the presence of Cad. Furthermore, Cu(b₆₄)B₁₂N₁₂ showed greater sensitivity to Cad compared to NO, H₂, H₂S, CO, COCl₂, N₂O, N₂ gases, or H₂O, showing high selectivity to diamine against interfering gases or water, standing out as a promising material for environmental applications in electronic, optical or work function sensors for cadaverine detection, even in humid environments.

Genetically encoded circuits have been successfully utilized to assess and characterize target variants with desirable traits from large mutant libraries. Adenosylcobalamin is an essential coenzyme that is required in many intracellular physiological reactions and is widely used in the pharmaceutical and food industries. High-throughput screening techniques capable of detecting adenosylcobalamin productivity and selecting superior adenosylcobalamin biosynthesis strains are critical for the creation of an effective microbial cell factory for the production of adenosylcobalamin at an industrial level. In this study, we developed an RNA-protein hybrid biosensor whose input part was an endogenous RNA riboswitch to specifically respond to adenosylcobalamin, the inverter part was an orthogonal transcriptional repressor to obtain signal inversion, and the output part was a fluorescent protein to be easily detected. The hybrid biosensor could specifically and positively correlate adenosylcobalamin concentrations to green fluorescent protein expression levels in vivo. This study also improved the operating concentration and dynamic range of the hybrid biosensor by systematic optimization. An individual cell harboring the hybrid biosensor presented over 20-fold higher fluorescence intensity than the negative control. Then, using such a biosensor combined with fluorescence-activated cell sorting, we established a high-throughput screening platform for screening adenosylcobalamin overproducers. This study demonstrates that this platform has significant potential to quickly isolate high-productive strains to meet industrial demand and that the framework is acceptable for various metabolites.