Biopolymers and cell. 1993. Volume 9. № 6. 31 - 35

KLIMENKO I. V., KORNELYUK A. I., MATSUKA G. Kh.

Conformational Change of Tyrosyl-tRNA Synthetase From Bovine Liver in the Course of Cognate tRNA Binding Revealed From Fluorescence Spectroscopy Data

Summary

    The fluorescent probe 1,5-1-AEDANS was covalently attached to tyro-syl-tRNA synthetase from bovine liver in a nearly stoichiometric amount (2 molecules of probe per enzyme dimer). Singlet-singlet energy transfer has been used for measurement of the apparent distance, between 6 tryptophan residues of enzyme and covalently attached 1,5-1-AEDANS. This distance was about 27.4 A assuming the random orientation of the donor and acceptor from polarization measurements. The interaction of cognate. tRNATyr with bovine tyrosyl-tRNA synthetase also resulted in the enhancement of fluorescence of AEDANS-labelled tyrosyRRNA synthetase (25 %) due to the increase of energy transfer efficiency. After binding of cognate bovine tRNATyr the apparent distance between tryptophan residues and AEDANS probe reduced to 25.3 A E. coll tRNAT>"r which was not aminoacylated by bovine enzyme did not induced these effects. Adding of ATP to the complex of bovine tRNAT^r and tyrosyl-tRNA synthetase exhibited further enhancement of AEDANS fluorescence by 32 %. In this case the apparent distance between tryptophan residues and AEDANS probe was 24.1 A. These results are consistent with the conforma-tional change of mammalian tyrosyl-tRNA synthetase, in the course of recognition of cognate tRNATy.