Natural-Abundance Carbon-13 Fourier-Transform Nuclear Magnetic Resonance Spectra and Spin Lattice Relaxation Times of Unfractionated Yeast Transfer-RNA*

AUTOR(ES)
RESUMO

High-resolution Fourier-transform nuclear magnetic resonance at 15.18 MHz was used to observe the proton-decoupled natural-abundance 13C spectra of aqueous unfractionated tRNA from baker's yeast in the presence of Mg+2 (8 ions per tRNA molecule), as a function of temperature in the range of 27-82°C. The spectrum of thermally denatured tRNA at 82°C showed numerous sharp resonances, which were assigned to specific types of carbon atoms by comparison with the 13C spectra of mononucleotides. Only the resonance of carbon 4′ of the ribose rings was appreciably shifted (by about 1.5 ppm upfield) with its average position in the mononucleotides. This effect was also seen in the spectrum of poly(A). In the spectrum of folded tRNA (52°C), carbon 4′ was further shifted upfield by about 1.5 ppm, and carbons 2′ and 3′, which yielded a single resonance at 82°C, now showed two partly resolved peaks.

ACESSO AO ARTIGO

Documentos Relacionados