Dioxaphosphorinane-Constrained Nucleic Acid Dinucleotides as Tools for Structural Tuning of Nucleic Acids

Table 4

Thermal melting temperatures (°C) of CNAgp within hairpin structures.

Entry	Sequence (5′-3′)^a	𝑇𝑚 (°C)^b	Δ𝑇𝑚 (°C)
1	ATCCTA TTTT TAGGAT	52.0	—
2	ATCCTA TxT TT TAGGAT	53.0	+1.0
3	ATCCTA T TxT T TAGGAT	55.0	+3.0
4	ATCCTA TT TxT TAGGAT	50.0	−2.0
5	ATCCTA TTT Tx TAGGAT	45.0	−7.0
6	AGGATCC TTTT GGATCCT	74.0	—
7	AGGATCC TxT TT GGATCCT	75.3	+1.3
8	AGGATCC T TxT T GGATCCT	77.5	+3.5
9	AGGATCC TT TxT GGATCCT	76.7	+2.7

^aTxT  denotes an (𝑆_C5′,𝑅_𝑃) 𝛼,𝛽-D-CNA-modified TT dinucleotide (CNAgp) and italic character denotes loop nucleotide. Underlined bases indicate the loop-closing base pair. ^bMelting temperatures (𝑇_𝑚 values) were measured as the maximum of the first derivate of the UV melting curve (OD₂₆₀ versus temperature, 20–90°C, 0.5°C/min) which was recorded at concentration around 5 𝜇M in sodium phosphate buffer (10 mM, pH 7.0) containing NaCl (100 mM) and EDTA (1 mM).