Table 4.

Comparison of Free-Energy Increments (kcal/mol at 37 °C) for Symmetric Tandem G•U, I•U, and A–U Motifs

adjacent base pairs	$\begin{array}{c}\text{UG}\\ \text{GU}\end{array}$	$\begin{array}{c}\text{UI}\\ \text{IU}\end{array}$	$\begin{array}{c}\text{UA}\\ \text{AU}\end{array}$	(UG–UI)	(UG–UA)
$\begin{array}{c}{5}^{\prime }\text{G}\\ 3^{\prime }\text{C}\end{array}$	−4.9a	-	−5.8a	-	0.9
$\begin{array}{c}{5}^{\prime }\text{C}\\ 3^{\prime }\text{G}\end{array}$	−4.2a	+0.5b	−5.5a	−4.7	1.3

adjacent base pairs	$\begin{array}{c}\text{GU}\\ \text{UG}\end{array}$	$\begin{array}{c}\text{IU}\\ \text{UI}\end{array}$	$\begin{array}{c}\text{AU}\\ \text{UA}\end{array}$	(GU–IU)	(GU–AU)
$\begin{array}{c}{5}^{\prime }\text{G}\\ 3^{\prime }\text{C}\end{array}$	−4.1a	-	−5.8a	-	1.7
$\begin{array}{c}{5}^{\prime }\text{C}\\ 3^{\prime }\text{G}\end{array}$	−1.1a	+2.1b	−5.3a	−3.2	4.2

^aRef 83.

^bRef 85.