Biochemistry30(13),3280–3289(1991), DOI10.1021/bi00227a016; indexed byline G. Varani, C. Cheong and I. Tinoco Jr. Abstract: NMR interproton distances/scalar couplings, constrained structural model and unusual loop contacts. Full Gabriele Varani byline also appears in the companion Nature346,680–682(1990), DOI10.1038/346680a0, www.nature.com/articles/346680a0 .