Proton magnetic resonance spectra of tRNA-Met-f from Thermus thermophilus.

220 MHz proton magnetic resonance spectra of tRNAs in bulk and tRNA-Met-f from Thermus thermophilus have been measured and compared with those of tRNAs from E. coli. Temperature dependences and chemical shift positions of the bulk tRNAs are well explained by the difference in their GC contents. It is known that the base sequence of the double helical regions in the cloverleaf structure of T. thermophilus tRNA-Met-f is different from that of E. coli tRNA-Met-f only at two positions in TpsiCarm; one more C:G pair is contained instead of a U:G pair of E. coli tRNA-Met-f and a C:G pair of E. coli is replaced by a G:C pair. In spite of the resembrance in the base sequences, nmr patterns around 13 ppm are fairly different from each other. The difference is discussed in relation with their tertiary structures and with the origin of chemical shift displacements.