Doornbos J, den Hartog JA, van Boom JH, Altona C. Conformational analysis of the nucleotides A2'-5'A, A2'-5'A2'-5'A and A2'-5'U from nuclear magnetic resonance and circular dichroism studies.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1981;
116:403-12. [PMID:
7250133 DOI:
10.1111/j.1432-1033.1981.tb05349.x]
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Abstract
In recent publications A2'-5'A2'-5'A was found to be an inhibitor of protein synthesis. In this research conformational analysis of the 2'-5'-linked nucleotides A2'-5'A, A2'-5'A2'-5'A and A2'-5'U is reported. The complete 1H-NMR assignment of the three compounds is given. The degree and mode of base-base stacking is extracted from coupling constant data and circular dichroic (CD) spectra at various temperatures. The 2'-5' nucleotides surprisingly show a much stronger tendency to stack than the 3'-5' compounds. At 85 degrees C A2'-5'A occurs for about 50% in stacked states. The mode of stacking is different from 3'-5'ribonucleotides where the sugar rings predominantly adopt an N conformation. A2'-5'U displays an A(S)2'-5'U(N) stacked state. In A2'-5'A 'mixed' modes of stacking, i.e. NN, NS, SN and SS, are proposed to account for the CD and NMR observations.
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