Solid-phase synthesis and structural characterisation of phosphoroselenolate-modified DNA: a backbone analogue which does not impose conformational bias and facilitates SAD X-ray crystallography

Conlon, P. F., Eguaogie, O., Wilson, J., Sweet, J. S. T., Steinhögl, J., Englert, K., Hancox, O. G. A., Law, C. J., Allman, S. A., Tucker, J. H. R., Hall, J. P. ORCID: https://orcid.org/0000-0003-3716-4378 and Vyle, J. S. (2019) Solid-phase synthesis and structural characterisation of phosphoroselenolate-modified DNA: a backbone analogue which does not impose conformational bias and facilitates SAD X-ray crystallography. Chemical Science, 10 (47). pp. 10948-10957. ISSN 1478-6524 doi: 10.1039/C9SC04098F

Abstract/Summary

Oligodeoxynucleotides incorporating internucleotide phosphoroselenolate linkages have been prepared under solid-phase synthesis conditions using dimer phosphoramidites. These dimers were constructed following the high yielding Michealis-Arbuzov (M-A) reaction of nucleoside H-phosphonate derivatives with 5ʹ-deoxythymidine-5ʹ-selenocyanate and subsequent phosphitylation. Efficient coupling of the dimer phosphoramidites to solid-supported substrates was observed under both manual and automated conditions and required only minor modifications to the standard DNA synthesis cycle. In a further demonstration of the utility of M-A chemistry, the support-bound selenonucleoside was reacted with an H-phosphonate and then after chain extension using phosphoramidite chemistry. Following initial unmasking of methyl-protected phosphoroselenolate diesters, pure oligodeoxynucleotides were isolated using standard deprotection and purification procedures and subsequently characterised by mass spectrometry and circular dichroism. The CD spectra of both modified and native duplexes derived from self-complementary sequences with A-form, B-form or mixed conformational preferences were essentially superimposable. These sequences were also used to study the effect of the modification upon duplex stability which showed context-dependent destabilisation (-0.4 ̶ -3.1 °C per phosphoroselenolate) when introduced at the 5ʹ-termini of A-form duplexes or at juxtaposed central loci within a B-form duplex (-1.0 °C per modification). As found with other nucleic acids incorporating selenium, expeditious crystallisation of a modified decanucleotide A-form duplex was observed and the structure solved to a resolution of 1.45 Å. The DNA structure adjacent to the modification was not significantly perturbed. The phosphoroselenolate linkage was found to impart resistance to nuclease activity.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/86671
Item Type	Article
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Optical Spectroscopy (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > School of Pharmacy > Medicinal Chemistry Research Group
Publisher	Royal Society of Chemistry
Download/View statistics	View download statistics for this item