Purine nucleoside synthesis, an efficient method employing nucleoside phosphorylases

Area of Science:

• Biochemistry
• Enzymology
• Synthetic Chemistry

Background:

• Pyrimidine nucleosides can serve as precursors for purine nucleoside synthesis.
• Enzymatic methods offer specificity and efficiency in nucleoside synthesis.

Purpose of the Study:

• To develop an improved enzymatic method for synthesizing purine nucleosides.
• To characterize the enzymes involved and optimize reaction conditions for yield.

Main Methods:

• Utilized pyrimidine nucleosides as pentosyl donors with uridine phosphorylase (Urd Pase) or thymidine phosphorylase (dThd Pase) and purine nucleoside phosphorylase (PN Pase).
• Enzymes were purified from Escherichia coli extracts using calcium phosphate gel titration and ion-exchange chromatography.
• Investigated enzyme stability across various pH levels, temperatures, and substrate concentrations.

Main Results:

• Optimized reaction conditions, including low phosphate concentrations, led to efficient product formation.
• Achieved high yields (81% and 76%) for the 2'-deoxyribonucleoside of 6-(dimethylamino)purine and the ribonucleoside of 2-amino-6-chloropurine, respectively.
• Determined pH optima and relative heat stability for Urd Pase, dThd Pase, and PN Pase, with stability enhanced by specific substrates and increasing enzyme concentration.

Conclusions:

• The described enzymatic method provides an efficient route for synthesizing diverse purine nucleosides.
• Understanding enzyme stability and optimizing reaction parameters are crucial for maximizing yields in enzymatic synthesis.
• This approach offers a valuable alternative for producing modified purine nucleosides.