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Thermostable valyl‐tRNA, isoleucyl‐tRNA and methionyl‐tRNA synthetases from an extreme thermophile Thermus thermophilus HB8: protein structure and Zn 2+ binding
Author(s) -
Kohda Daisuke,
Yokoyama Shigeyuki,
Miyazawa Tatsuo
Publication year - 1984
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(84)81069-8
Subject(s) - thermus thermophilus , transfer rna , thermophile , amino acyl trna synthetases , biochemistry , biology , aminoacyl trna synthetase , enzyme , thermus , amino acid , dimer , rna , chemistry , escherichia coli , gene , organic chemistry
Thermostable valyl‐tRNA, isoleucyl‐tRNA and methionyl‐tRNA synthetases have been purified from an extreme thermophile, Thermus thermophilus HB8. Valyl‐tRNA and isoleucyl‐tRNA synthetases are found to be monomer proteins ( M r 108000 and 129000, respectively), while methionyl‐tRNA synthetase is a dimer protein ( M r 150000). These enzymes are very similar with respect to amino acid compositions and α‐helix contents as estimated by circular dichroism analyses. Furthermore, two Zn 2+ are tightly bound to each of these synthetases. These data suggest that valyl‐tRNA and isoleucyl‐tRNA synthetases consist of two domains, each corresponding to the subunit of methionyl‐tRNA synthetase.