[Primary and spatial structure of tRNA].

The recent achievements in studying of structure of tRNA are considered in the present paper. A brief analysis of the new methods for sequencing tRNA was carried out. Due to the development of these methods about 300 tRNA primary structures have been determined. Comparison of the primary tRNA structures gives us the possibility to divide them into seven classes: prokaryotic initiator tRNAs and eukaryotic initiator tRNAs; prokaryotic elongator tRNAs and eukaryotic elongator tRNAs; archaebacterial tRNAs; and mitochondrial tRNAs of lower and higher eukaryotes. Structural properties of the tRNAs of each of these classes are discussed. The second part of the paper is devoted to the three-dimensional structure of tRNA. Recent data in this field obtained by X-ray crystallographic technique as well as by high-resolution NMR and chemical modification methods are reviewed.