Table 2. Lookup table for unstable triloops and stable tetraloops and hexaloops.

Hairpin	Ref(s).	ΔG°37 loop, kcal/mol
CAACG	87	6.8
GUUAC	87	6.9
CAACGG	48	5.5
CCAAGG	48	3.3
CCACGG	48	3.7
CCCAGG	48	3.4
CCGAGG	48	3.5
CCGCGG	48	3.6
CCUAGG	48	3.7
CCUCGG	48	2.5
CUAAGG	48	3.6
CUACGG	47, 50	2.8
CUCAGG	48	3.7
CUCCGG	47	2.7
CUGCGG	47	2.8
CUUAGG	48	3.5
CUUCGG	47, 50	3.7
ACAGUACU	86	2.8
ACAGUGCU	86	2.9
ACAGUGAU	86	3.6
ACAGUUCU	86	1.8

For extra stable hairpins measured in 0.1 M Na⁺ (48, 87), placement was determined by assuming that the relative stability of loops remains constant between 0.1 and 1 M Na⁺. All values are based on experimental results rather than frequencies of occurrence as used in ref. 8. Unpaired nucleotides are shown in bold.