(449cj) Continuous separation of four 5′-ribonucleotides based on ion exchange

5â?²-ribonucleotides have been widely used in food and pharmacutical industry. They can enhance immunity and promote metabolism of lipoprotein and long-chain polyunsaturated fatty acids as food additives. They also can be used to synthetise antiviral and anticancer pharmaceuticals, and their derivatives play a significant role in treatment of some diseases related with human central nervous system and blood circulation system. The separation and purification of 5â?²-ribonucleotides is one of the significant steps in industrial production. A continuous separation process was developed to separate four 5â?²-ribonucleotides (Uridine 5â?²-monophosphate (UMP), Adenosine 5â?²-monophosphate (AMP), Cytidine 5â?²-monophosphate (CMP), and Guanosine 5â?²-monophosphate (GMP)) from enzymatic hydrolysate of RNA based on ion exchange with a strong-acid cation exchange resin NH-1 used as ion exchanger. The process contains three zones including loading, elution, and regeneration. Deionized water was used as eluent to elute UMP and GMP. 0.2 mol/L NaOH aquous solution was used as eluent to elute CMP and AMP. The purity of AMP, CMP, and GMP in the eluent is close to 100%. The purity of UMP in the eluent is about 80% which can be readily purified by an additional anion exchange resin. The recovery percentage of UMP approaches to 100%. The recovery percentages of CMP and GMP are all about 95%. The recovery percentage of AMP is about 90%. In the zone for regeneration, the impurity including pigment retaining in the resin was eluted by 1.2 mol/L NaOH aquous solution, and then the resin was converted to hydrogen form by 1.2 M HCl. Then the ion exchange equilibrium behaviors of 5â?²-ribonucleotides on the resin NH-1 were studied. UMP is not retained by the resin because the amino group in UMP molecule can not ionize. Positively charged forms of AMP, CMP, and GMP can be uptaken by the resin through ion exchange with the hydrogen ion on the resin. AMP and GMP zwitter ions can be retained on the resin through physical interaction. In addition to coulomb force, the physical interactions including Van der waals force and hydrophobic interaction etc. between 5â?²-ribonucleotides and resin can also affect the affinity of the resin to 5â?²-ribonucleotides molecules. The affinity sequence of the resin NH-1 to AMP, CMP, and GMP is identical to the hydrophobicity sequence of them. Higher hydrophobicity leads to higher affinity. A mathematical model based on solution phase dissociation equilibrium, ion exchange and distribution equilibrium was developed to fit the uptake equilibrium data of Na⁺, AMP, CMP, and GMP on the resin in single systems. The model with the selectivity and distribution coefficients from single systems predicted the uptake equilibrium relationship of 5â?²-ribonucleotides and Na⁺ on the resin in the multicomponent systems successfully.