In:
European Journal of Biochemistry, Wiley, Vol. 55, No. 3 ( 1975-07), p. 517-529
Abstract:
Complexes between tRNA Phe (yeast), tRNA Ser (yeast) and tRNA Tyr ( Escherichia coli ) and their cognate aminoacyl‐tRNA synthetases have been studied by sedimentation velocity runs in an analytical ultracentrifuge. The amount of complex formation was determined by the absorption and the sedimentation coefficients of the fast‐moving boundary in the presence of excess tRNA or excess synthetase respectively. The same method has been applied to unspecific combinations of tRNAs and synthetases. Inactive material of tRNA or synthetase does not influence the results. Two moles of tRNA Phe can be bound to one mole of phenylalanyl‐tRNA synthetase with a binding constant ≫ 10 6 M −1 . The binding constants for both tRNAs are very similar; the binding sites are independent of each other. Omission of Mg 2+ does not prevent binding. Two moles of tRNA Ser can be bound to one mole of Seryl‐tRNA synthetase; the binding of the first and second tRNA is non‐equivalent. K 1 ≫ 10 6 M −1 , K 2 is determined to be 1.3×10 5 M −1 at pH 7.2. Omission of Mg 2+ prevents complex formation. Tyrosyl‐tRNA synthetase behaves very similarly to seryl‐tRNA synthetase. The binding constant for the weakly bound tRNA is 2.3×10 5 M −1 at pH 7.2, and 2.5×10 6 M −1 at pH 6.0. No complexes are observed in the absence of Mg 2+ . Unspecific binding was only obtained with phenylalanyl‐tRNA synthetase. It binds tRNA Ser (yeast), tRNA Ala (yeast) and tRNA Tyr ( E. coli ) with a binding constant about 100 times lower compared to its cognate tRNA. The binding data are discussed with respect to the tertiary structure of the tRNAs, the subunit structure of the synthetases and the possible physical basis for the non‐equivalence of binding sites.
Type of Medium:
Online Resource
ISSN:
0014-2956
,
1432-1033
DOI:
10.1111/ejb.1975.55.issue-3
DOI:
10.1111/j.1432-1033.1975.tb02189.x
Language:
English
Publisher:
Wiley
Publication Date:
1975
detail.hit.zdb_id:
1398347-7
detail.hit.zdb_id:
2172518-4
SSG:
12
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