Interaction of La(III) and Tb(III) ions with purine nucleotides: Evidence for metal chelation (N-7-M-PO3) and the effect of macrochelate formation on the nucleotide sugar conformation
✍ Scribed by Heidar-Ali Tajmir-Riahi
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1991
- Tongue
- English
- Weight
- 860 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Abstract
The interaction of the La(III) and Tb(III) ions with adenosine‐5′‐monophosphate (5′‐AMP), guanosine‐5′‐monophosphate (5′‐GMP), and 2′‐deoxyguanosine‐5′‐monophosphate (5′‐dGMP) anions with metal/nucleotide ratios of 1 and 2 has been studied in aqueous solution in acidic and neutral pHs. The solid complexes were isolated and characterized by Fourier transform ir and ^1^H‐nmr spectroscopy.
The lanthanide(III)–nucleotide complexes are polymeric in nature both in the solid and aqueous solutions. In the metal‐nucleotide complexes isolated from acidic solution, the nucleotide binding is via the phosphate group (inner sphere) and an indirect metal‐N‐7 interaction (outer‐sphere) with the adenine N‐1 site protonated. In the complexes obtained from neutral solution, metal chelation through the N‐7 and the PO group is prevailing. In aqueous solution, an equilibrium between the inner and outer sphere metal‐nucleotide interaction has been observed. The ribose moiety shows C2′‐endo/anti pucker in the free AMP anion and in the lanthanide(III)–AMP complexes, whereas the GMP anion with C2′‐endo/anti sugar conformation exhibits a mixture of the C2′‐endo/anti and C3′‐endo/anti sugar puckers in the lanthanide(III)–GMP salts. The deoxyribose has O4′‐endo/anti sugar pucker in the free dGMP anion and a C3′‐endo/anti, in the lanthanide (III)–dGMP complexes.