We have been collecting footprinting data on the Tetrahymena Group I ribozyme. We've collected data on 10 mutants, sequentially knocking out each of the five contacts (alpha, beta,gamma,delta and epsillon). We collected titration data for a number of salts including Mg, Na, Urea etc. We wanted to observe the formation of these contacts as a function of Mg, Na and Urea concentration.