Specific protein-nucleic acid recognition in ribonuclease T1-2'-guanylic acid complex: an X-ray study

RNase T1 is folded into an alpha-helix of 4.5 turns, covered by a four-strand antiparallel beta-sheet. Specific recognition of 2'-guanylic acid arises from hydrogen bonding between main chain peptide groups and the O-6 and N-1-H of guanine, as well as from stacking of Tyr 45 on guanine. At the active site, Glu 58, His 92 and Arg 77 are involved in phosphodiester hydrolysis.