Isotopic hydrogen exchange in the dinucleoside monophosphate IpI

✍ Scribed by G. J. Thomas Jr; S. A. Ferreira

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 272 KB
• Volume: 12
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.1250120206

✦ Synopsis

Abstract

Each of the hypoxauthine residues of the dinucleoside monophosphate, inosylyl(3′→5′)inosine (IpI), manifests the same rate of deuterium exchange of the proton at the 8‐C ring position, as measured by Raman spectrophotometry. In the temperature interval 30–80°C and at neutral pD, the exchange rate constants yield Arrhenius parameters (E~a~ = 22.4±0.6 kcal mol^−1^; A = 2.13 × 10^13^ h^−1^) that are identical to values obtained on inosine‐3′:5′‐monophosphate (cIMP), but different from those of inosine‐5′‐monophosphate (5′‐IMP) which exchanges more slowly. The results confirm that nucleotides containing the monovalent phosphate anion, exchange more rapidly than those containing the divalent phosphate anion, and suggest further that base stacking in IpI does not greatly retard the speed of 8‐CH exchange of either of the hypoxanthine rings.