Nucleoside analogues have been in clinical use for almost 50 years and have become cornerstones of treatment for patients with cancer or viral infections. Furthermore, nucleoside analogues can be used as immunosuppressive drugs. Therefore, Azathioprine, a purine analogue, is used in organ transplantation and for treatment of autoimmune diseases. Cladribine also possesses specific activity on lymphocytes and has been evaluated in patients with autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. The approval of several additional drugs over the past decade demonstrates that this family still possesses strong potential.


Modified nucleosides are currently produced through a long and tedious chemical process that limits the production of new compounds. Consequently, new and more efficient synthesis methods are of high interest. We are presenting an enzymatic alternative to chemical methods using thermostable nucleoside phosphorylases.


Despite the very impressive progress achieved in the development of chemical methods, the preparation of purine nucleosides remains a challenging problem. A common drawback of often used approaches is the indispensable introduction and subsequent removal of protective groups, which is associated with chromatographic purification in almost every step, a lack of selectivity of chemical reactions, and the problems associated with the poor regio- and stereoselectivity of chemical reactions. In contrast, the enzymatic synthesis of nucleosides by the transglycosylation reaction proceeds with strict stereo- and regioselectivity and requires organic solvents only for the isolation of the individual desired compound. The production process becomes sustainable and products with a purity >99% are achieved. Production time and costs are drastically reduced.


BioNukleo is an expert for the production of nucleoside phosphorylase enzyme kits. Consequently, customers will be able to design their own nucleosides and can order large batches of their favorite phosphorylase. We are also vending several kits of nucleoside kinases for the production of nucleotide analogues. Finally, our library of in-house synthesized high quality nucleoside analogues proofs the enzyme technology. However, BioNukleo offers custom synthesis of enzymes and nucleosides. 

Nucleoside phosphorylases from thermophiles

The chemical modification of pyrimidine nucleosides is generally well established, however, the synthesis of modified purine nucleosides is often more challenging. The chemo-enzymatic synthesis of purine nucleosides from a pyrimidine nucleoside serving as pentofuranosyl donor and a purine base functioning as pentofuranosyl acceptor is an alternative and can be performed with nucleoside phosphorylases (NPs) as biocatalysts. Unfortunately, a number of highly interesting nucleoside analogues are hardly recognized as substrate by NPs of mesophilic microorganisms that are currently in use. Moreover, high temperatures are desirable to increase the concentration of poorly soluble purine bases. Both factors prompted us to study use thermostable nucleoside phosphorylase variants as biocatalysts for the production of modified nucleoside. A set of 7 nucleoside phosphorylases is available.

Nucleoside deoxyribosyltransferases

Nucleoside deoxyribosyltransferases (NDTs) catalyse the direct transfer of the 2’-deoxyribosyl moiety from a 2’-deoxyribosyl nucleoside to a free nucleobase without formation of intermediate 2-deoxyribofuranose-1-phosphate (dR-1-P), and phosphate in not involved. Due to a higher activity against 2´-modified nucleosides our enzyme library was extended a number of NDTs of thermophilic organisms.


Nucleoside and nucleotide kinases are used to produce 5´-phophorylated ribo- and deoxyribonucleosides. All intermediates to (deoxy)ribonucleotides can be produced using our enzymes. The enzymes were shown to also use modified nucleosides or nucleotides as substrate.