1990•PubMedRequires access
Comparative study of the phenylalanyl-tRNA synthetases from Escherichia coli and Thermus thermophlus by the tritium topography method.
Ekaterina V. Bobkova, A V Gedrovitch, Valentina N. Ankilova, O I Lavrik, Liudmila A. Baratova, Alexander V. Shishkov
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Abstract
A comparative study of thermostability and aminoacid composition of the phenylalanyl-tRNA synthetases from E. coli and Thermus thermophilus HB8 has been carried out. Compared with the mesophilic enzyme, a considerable increase of Pro, Leu, Phe, Arg and decrease of Asx, Ile, Ser, Thr and Lys content have been revealed in the thermophilic protein. Using tritium topography, Pro, (Leu + Ile) and Gly were found to be the most accessible on the surfaces of both the enzymes. In the E. coli enzyme, Thr residues were also easy to access while on the surface of the thermophilic enzyme there were more Arg residues. The quantitative assay of the surface compositions revealed the increased exposure of the (Leu + Ile) residues on the thermophilic protein as well as of the charged Asx and Arg residues. A possible correlation of the observed effects with thermostability is discussed.