Various types of 5s rRNA crystals as studied by X-ray diffraction and electron microscopy

Six different types of 5 S rRNA crystals were obtained using the specimen purified from highly thermophilic bacteria, Thermus thermophilus HB8. The best crystal available diffracts X-rays up to 13A Bragg spacing. One type of crystals was sufficiently thin to be subjected to electron microscopy. Optically filtered images of two different projections exhibit molecular regions distinctly from the medium. Preliminary investigation of packing of the molecules into the unit cell gives some implication of their overall shape.