The self-splicing RNA of Tetrahymena is trapped in a less active conformation by gel purification.

When the circular form of the self-splicing intervening sequence of Tetrahymena thermophila was purified by denaturing polyacrylamide gel electrophoresis by standard methods, the rate of its reaction with tetrauridylate decreased 150-fold at 30 degrees C and at least 1000-fold at 0 degrees C. The activity of the self-splicing RNA was restored by heating it to high temperature and letting it renature in the presence of Mg2+. The rate of reaction of tetrauridylate with the self-splicing RNA flanked by exons was also greatly decreased by gel purification. The difference in activation energies for the reaction of native and denatured intervening sequences suggests that a substantial conformational rearrangement of the gel-purified RNA occurs prior to reaction.