246D:
reference: Structure of the purine-pyrimidine alternating RNA double helix, r(GUAUAUA)d(C), with a 3'-terminal deoxy residue., Wahl MC, Ban C, Sekharudu C, Ramakrishnan B, Sundaralingam M, Acta Crystallogr D Biol Crystallogr. 1996 Jul 1;52(Pt 4):655-67. PMID: 15299629

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