Changes in the ultraviolet absorption of E. coli rRNA on ribosome unfolding

Escherichia coli ribosome unfolding in low Mg2+solutions observed by laser Raman spectroscopy and electron microscopy

“…Taken together, the Raman and CD results are consistent with the breaking up of base pairs in some rRNA helices during unfolding, with a change in the ribose conformation of the involved nucleotides, but without base unstacking. This interpretation is also consistent with UV absorption data (6), which demonstrate no change in absorbance at 260 nm during unfolding, and only a small (1-2%) hyperchromic effect at 280 nm, implying little or no base unstacking.…”

“…These studies generally reinforce conclusions drawn from Gesteland's sedimentation analysis, but they do not yield additional information about the conformation of unfolded ribosomes. The ultraviolet absorption and circular dichroism of unfolded ribosomes have provided some information about the unfolding reaction at the molecular level (4)(5)(6), but the precise interpretation of some of these data is uncertain.…”