Oligonucleotide studies: optical rotatory dispersion of normal and 2′‐ O ‐methylated diribonucleoside monophosphates
1971; Wiley; Volume: 10; Issue: 12 Linguagem: Inglês
10.1002/bip.360101208
ISSN1097-0282
AutoresHarwant Singh, Brian J. Hillier,
Tópico(s)Neonatal Health and Biochemistry
ResumoAbstract The optical rotatory dispersion (ORD) of several diribonucleoside monophosphates (NpN) and the corresponding 2′‐ O ‐methyl substituted dinucleoside monophosphates containing 2′‐ O ‐methyl ribosyl 3′‐nucleotide and a 5′‐nucleoside (NmpN) were measured at pH 1, 7, and 11.2, at 0.1 ionic strength in order to examine the role of the 2′‐hydroxyl group of the ribose in the conformation of the oligoribonucleotides. The optical measurements are reported from 210 to 340 mμ. The pH effect on the ORD spectra of NpN as well as NmpN are large. No dramatic changes are seen in the shapes of the ORD spectra of the NmpN to the corresponding NpN at pH 7. However, a decrease in the amplitude is seen in most of the NmpN over that of the corresponding NpN ranging from 7 percent in the case of UmpG to 46 percent in AmpA. The differences seen in the NpN and the corresponding NmpN ORD results are best explained as a consequence of a change in the ribosyl conformation on 2′‐ O ‐methylation, rather than the involvement of the 2′‐hydroxyl group in intramolecular hydrogen bonding in the ribo dimmer. The NmpN behave like NpN and not dNpdN, suggesting that the geometry of the stack in NpmN and NpN depends on the oxygen at the 2′‐carbon and not on what is attached to it.
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