Influence of Modified tRNATyr on the Activation of Tyrosine Catalyzed by Tyrosyl-tRNA Synthetase from Saccharomyces cerevisiae

Gruić-Sovulj, Ita and Weygand-Đurašević, Ivana and Kućan, Željko (2001) Influence of Modified tRNATyr on the Activation of Tyrosine Catalyzed by Tyrosyl-tRNA Synthetase from Saccharomyces cerevisiae. Croatica Chemica Acta, 74 (1). pp. 161-171. ISSN 0011-1643

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Abstract

Yeast tyrosyl-tRNA synthetase (TyrRS, EC 6.1.1.1) is a homodime- ric enzyme capable of binding only one molecule of its macromolecular substrate, tRNATyr. The reactive intermediate tyrosyl adenylate is formed from tyrosine and ATP in the first reaction step, which can be conveniently assayed by pyrophosphate exchange. In order to determine the number of active sites per homodimer, the kinetics of pyrophosphate exchange was measured in the presence of the tRNATyr analogue unable to accept the amino acid. The analogue was found to form the expected equimolar complex with dimeric enzyme. It was a competitive inhibitor of pyrophosphate exchange with respect to ATP and non-competitive with respect to tyrosine. Inhibition cannot exceed 50%, suggesting the simplest model in which yeast TyrRS is a symmetrical dimer, possessing two identical active sites, both capable of catalyzing the formation of tyrosyl adenylate.

Item Type: Article
Keywords: modified tRNATyr; pyrophosphate exchange; Saccharomyces cerevisiae; tyrosyl-tRNA synthetase; tRNATyr
Date: 2001
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Faculty of Science > Department of Chemistry
Publisher: Hrvatsko kemijsko društvo
Related URLs:
Depositing User: mag. bibl. Ana Šafran
Date Deposited: 23 May 2014 10:55
Last Modified: 23 May 2014 10:55
URI: http://digre.pmf.unizg.hr/id/eprint/1641

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