Spermine binds in solution to the T(psi)C loop of tRNA(Phe): evidence from a 750 MHz 1H-NMR analysis

A method based on 1H-1H NOE interactions is used to identify the binding site of spermine on tRNA. The carbon-bound methylene protons next to the amino groups are used to follow the interaction with tRNA. These protons resonate between 2.8-3.1 ppm where they overlap with the tRNA sugar resonances. This overlap is resolved by using spermines enriched with 13C in the carbons bonded to the -NH2+- and NH3+ groups. Results show that spermine interacts at the corner of the L-shaped tRNA molecule where the T_C and D loops intersect. These results are useful in the further understanding of the function of polyamines in cell growth and carcinogenesis.