Arrangement of the Helical Regions in E. coli Tyrosine tRNA

Abstract

X-RAY observations on a crystalline preparation of ^tRNA^Met_F from E. coli have recently been reported¹. The specimen consisted of an unoriented array of microcrystals and the crystalline X-ray reflexions extended to approximately 25 Å. The crystallization shows that this tRNA has a well defined structure, and raises the prospect of making crystals of suitable quality for detailed X-ray analysis. It may be that such improvement in the crystallinity will require some time and effort, however, and therefore interpretations of the diffraction data will have to be attempted using information from other sources about tRNA. The clover leaf structure of tRNA² might be taken as a starting point and information on the arrangement of the various arms used to construct a first trial model the structure and packing of which in the unit cell can then be refined to give the best agreement with the crystalline tRNA X-ray data.