Comparative study of subunits of phenylalanyl-tRNA synthetase from Escherichia coli and Thermus thermophilus
- 23 September 1991
- journal article
- Published by Wiley in FEBS Letters
- Vol. 290 (1-2), 95-98
- https://doi.org/10.1016/0014-5793(91)81234-y
Abstract
FPLC separation of α- and β-subunits of phenylalanyl-tRNA synthetases from E. coli MRE-600 and Thermus thermophilus HB8 has been carried out in the presence of urea. Native α-subunits of both enzymes were primarily α2-dimers and tended to aggregate. Most E. coli enzyme β-subunits were monomeric and only a small fraction was represented by β2-dimers. All thermophilic β-subunits were β-dimers. It was shown that monomers and all forms of homologous subunits had no catalytic activity in tRNAPhe aminoacylation. For the enzymes and their subunits, titration curves were obtained and isoelectric points were determined. The comparison of the relative surface charges indicated similarity of the surfaces of entire enzymes and the corresponding β-subunits. α-Subunits displayed a distinctly different pH dependence of the surface charge. A spatial model of the oligomeric structure and a putative mechanism for its formation are discussedKeywords
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