Table 2.

Lookup table for unstable triloops and stable tetraloops and hexaloops

Hairpina	Ref(s)b	$\Delta H_{\text{loop}}^{°}$ (kcal/mol)
CaacG	A	23.7
GuuaC	A	10.8
CaacgG	B	6.9
CcaagG	B	−10.3
CcacgG	B	−3.3
CccagG	B	−8.9
CcgagG	B	−6.6
CcgcgG	B	−7.5
CcuagG	B	−3.5
CcucgG	B	−13.9
CuaagG	B	−7.6
CuacgG	C, D	−10.7
CucagG	B	−6.6
CuccgG	C	−12.9
CugcgG	B	−10.7
CuuagG	B	−6.2
CuucgG	C, D	−15.3
CuuugG	D	−6.8
AcaguacU	E	−16.8
AcagugcU	E,C	−12.8
AcagugaU	C	−11.4
AcaguguU	E	−15.4

Closing pairs are included and unpaired nucleotides are shown in lower case.

^aFor extra stable hairpins measured in 0.1 M Na⁺ (A, B), placement was determined by assuming that the relative enthalpy of loops remains constant between 0.1 and 1 M Na⁺(30,34).

^bA, Ref. (34); B, Ref. (35); C, Ref. (30); D, Ref. (31); E, Ref. (36).