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Denaturation of UGA suppressor tRNATrp from E. coli

1974; Elsevier BV; Volume: 56; Issue: 1 Linguagem: Inglês

10.1016/s0006-291x(74)80307-4

1090-2104

Richard H. Buckingham, Antoine Danchin, M. Grunberg‐Manago,

Enzyme Structure and Function

Summary To help elucidate the structure of inactive tRNATrp ( E. coli ), reversible denaturation has been studied in the UGA suppressor tryptophan tRNA from strain CAJ64, which has an A. U instead of G. U pair in the dihydrouridine stem, and is more stable than the wild type tRNA. The Su+ tRNA is half-denatured at 10 mM Na+, in the absence of magnesium, at 55°C, compared to 1M Na+ for the wild type tRNA. Denatured Su+ tRNA is less stable than the wild type, and ΔHr* in 5 mM Mg2+ is 33 kcal/mole compared to 74 kcal/mole. These results favour the hypothesis that guanidine-24 pairs with a cytidine in the metastable denatured form.