Strong Binding and Off–On Signaling Functions of Deep-Red Fluorescent TO-PRO-3 for Influenza A Virus RNA Promoter Region

The RNA promoter region of the influenza A virus has recently attracted much attention as an RNA target for the development of anti-influenza drugs. However, there are very few reports on small RNA-binding ligands targeting this region. In this work, it is reported that TO-PRO-3, a thiazole orange analogue with a trimethine bridge, exhibits strong and selective binding to the internal loop structure of the influenza A virus RNA promoter. This binding accompanies the remarkable light-up response of TO-PRO-3 in the deep-red spectral region. By virtue of these binding and fluorescence signaling functions, TO-PRO-3 can act as a useful indicator for the assessment of the binding capabilities of various test compounds for this RNA region, with a view toward the development of anti-influenza drug candidates.     

Design and optimization of JO-IEX process for highly efficient quaternary separation of 5′-ribonucleotides

The developed JO-IEX technology was applied to continuously separate four 5′-ribonucleotides here. The unit contained seven columns with three separation steps, among which three columns were for the quaternary separation and the others for regeneration of resins. The operating conditions, that is, the critical flow rates in three separation steps were preliminarily designed according to the equilibrium theory and optimized by a three-dimensional theoretical separation region approach. The feasibility of the JO-IEX process and the separation performances were validated by four runs using the actual 5′-ribonucleotides' enzymatic hydrolysate as feed solutions. The purities and yields of 5′-ribonucleotides could reach above 97%. The productivity was enhanced to be 0.91 g/(kg h), and the desorbent consumption was reduced to be 1.01 L/g, compared to those of 0.70 g/(kg h) and 1.75 L/g in the fixed-bed process. The technology proposed could be a potential technique in the continuous multicomponent ion-exchange separation process.