Orientation of double-helical segments in crystals of yeast phenylalanine transfer RNA

A search of the X-ray intensities of the P21 crystal form of yeast transfer RNAPhe has revealed the orientation of the double-helical segments in the crystal. Because of the ambiguity imposed by the crystal symmetry on choosing the helices belonging to the same molecule, and because of the difficulty of determining lengths and positions of helices, a unique model cannot be deduced, but only a small number of types are possible. Among the...