[Immunochemical study of tryptophanyl-tRNA-synthetase].

The immunochemical approach used extensively in medicine and in some fields of biology has not yet been systematically applied to enzymology, in particular, to the study of a large, functionally significant group of enzymes, such as aminoacyl-tRNA synthetases (EC 6.1.1). The present investigation was aimed at the analysis of applicability of polyclonal and monoclonal antibodies against bovine tryptophanyl-tRNA synthetase in the study of functional properties of this enzyme as well as of its distribution inside the cell and among organs and tissues of various animals. The general conclusions one may draw from these data are as follows. i) Tryptophanyl-tRNA synthetase of eukaryotes, eubacteria and archaebacteria share one common structural element (antigenic determinant) that is not essential for the catalytic activity. The evolutionary conservative nature of this element suggests that the enzyme may implement functions other than catalysis of tryptophanyl-tRNA formation. ii) Tryptophanyl-tRNA synthetase shows an anomalous distribution among mammalian organs: its content is far greater in the exocrine part of the ruminant animal pancreas in comparison with their other organs (liver) or with other mammalian orders. This finding suggests that the enzyme or its fragments may play a role in the digestive function of ruminant animals. iii) Tryptophanyl-tRNA synthetase was found in considerable quantities in diffuse chromatin of mammalian cell nuclei. This fact indicates that the enzyme may participate in such processes in the nucleus as transcription, processing, transport, etc. It may thus be concluded that tryptophanyl-tRNA synthetase of higher organisms, besides catalyzing the formation of aminoacyl-tRNAs can exert some other, yet unknown, noncanonical functions.