Preparation of Vanadyl-Ribonucleoside Complexes that Inhibit Ribonuclease Activity

• Vanadyl sulfate
• Adenosine
• Cytidine
• Guanosine
• Uridine
• 10 N NaOH

1. Make 10 mL 2 M vanadyl sulfate (0.366 g/mL).
2. To make 80 mL H₂O in a 250-mL flask, add 1.34 g adenosine, 1.45 g guanosine, 1.25 g uridine, and 1.25 g cytidine = 5 mM XRs.
3. Boil in H₂O bath with N₂ sparge (XRs dissolve but precipitate upon cooling).
4. Add vanadyl sulfate and continue to boil and sparge 1 min (solution should remain blue).
5. Turn off H₂O bath, continue to sparge, and add 8 mL 10 N NaOH, then 4 mL 1 N NaOH (ugly gray precipitate; redissolve when all NaOH added) check pH = 7–9 range.
6. Resulting 0.2 M vanadyl nucleoside solution stored at –20°C.
7. Upon thawing, redissolve precipitate at 65°C.