. Author manuscript; available in PMC: 2019 Jun 11.

Published in final edited form as: Biochemistry. 2019 Jan 31;58(8):1094–1108. doi: 10.1021/acs.biochem.8b01027

Table 4.

Free energy increments for 2×2 nt internal loops along with whether NMR detected wobble GU pairs are present.

Internal Loop⁷	2×2 Measured ΔG°₃₇ (kcal/mol)⁷	2×2 Predicted ΔG°₃₇ (kcal/mol)⁵	2×2 \|ΔΔG\| (kcal/mol)	4×4 Measured ΔG°₃₇ (kcal/mol)⁷	4×4 Predicted ΔG°₃₇ (kcal/mol)⁵⁶	4×4 \|ΔΔG\| (kcal/mol)	Wobble GU
5’-GCAU/3’-UACG	3.6	3.0	0.6	0.0	2.2	2.2	Y
5’-UUCG/3’-GCUU	4.3	3.0	1.3	2.9	3.6	0.7	Y
5’-GCUU/3’-UUCG	5.4	3.0	2.4	4.6	3.6	1.0	N
5’-GUCU/3’-UCUG	4.1	3.0	1.1	3.4	3.6	0.2	N
5’-GCCU/3’-UCCG	5.1	3.0	2.1	4.4	3.6	0.8	N
5’-GAAU/3’-UAAG	5.4	3.0	2.4	4.5	3.6	0.9	N^a
5’-GACU/3’-UCAG	3.6	3.0	0.6	2.8	3.6	0.8	N^a

^a:

Lack of a GU wobble pairing is inferred from 1D spectra.⁷