Method of purifying cytidine diphosphate choline
A method of purifying cytidine diphosphate choline, which comprises contacting a cytidine diphosphate choline solution containing a nucleic acid analogue and having a pH of not less than 0.5 and not more than 5.0 with an H-type strongly acidic cation exchange resin, and eluting cytidine diphosphate choline adsorbed onto the resin with water or an aqueous solution having an ion concentration of not more than 0.1 mol/L to separate and purify the cytidine diphosphate choline.
1. A method of purifying cytidine diphosphate choline (CDP-choline), which method comprises
a) contacting a CDP-choline solution having a pH of 0.5 to 5.0 and containing an impurity comprising a nucleic acid analogue with an H-type strongly acidic cation exchange resin of a gel type or a porous type which has a degree of crosslinking of 2-10%, wherein the CDP-choline binds to the resin and the nucleic acid analogue does not bind to the resin, and
b) eluting the CDP-choline adsorbed onto the resin with water or an aqueous solution having an ion concentration of not more than 0.1 mol/L, thereby purifying CDP-choline from the nucleic acid analogue.
2. The method of claim 1 , wherein the CDP-choline solution is prepared from a resulting medium containing CDP-choline, which has been produced and accumulated therein by bringing a biocatalyst having an activity to produce CDP-choline from a precursor of uridine-5′-triphosphate (UTP) and choline or phosphorylcholine in an aqueous medium into contact with the precursor of UTP and choline or phosphorylcholine or a salt thereof.
3. The method of claim 2 , wherein the biocatalyst comprises a culture or a treated culture of a microorganism capable of producing UTP from a precursor of UTP, and a culture or a treated culture of a microorganism capable of producing CDP-choline from UTP and choline or phosphorylcholine.
4. The method of claim 2 , wherein the biocatalyst comprises an enzyme that catalyzes a reaction to produce CDP-choline from a precursor of UTP and choline or phosphorylcholine.
5. The method of claim 4 , wherein the enzyme that catalyzes a reaction to produce CDP-choline is an enzyme selected from the group consisting of orotate phosphoribosyl transferase, orotidine-5′-monophosphate decarboxylase, uridine phosphorylase, uracil phosphoribosyltransferase, uridine kinase, uridylate and cytidylate kinases, nucleoside diphosphate kinase, cytidine-5′-triphosphate synthase, choline phosphate cytidyltransferase and choline kinase.
6. The method of claim 1 , wherein the nucleic acid analogue is selected from uracil and UTP.