Journal of the Brazilian Chemical Society
versão On-line ISSN 1678-4790
FRYDMAN, Benjamin et al. Regioselective binding of spermine, N1,N12-bismethylspermine, and N1,N12-bisethylspermine to tRNAPhe as revealed by 750 MHz 1H-NMR and its possible correlation with cell cycling and cytotoxicity. J. Braz. Chem. Soc. [online]. 1999, vol.10, n.4, pp. 334-340. ISSN 1678-4790. http://dx.doi.org/10.1590/S0103-50531999000400014.
The binding of spermine (SPM), N1,N12-bismethylspermine (BMS) and N1,N12-bisethylspermine (BES) to tRNAPhe was studied using 1H-NMR at 750 MHz. The polyamines were enriched in 13C at the 5-CH2 and 8-CH2 residues and the nuclear Overhauser enhancement (NOE) cross peaks connecting the 1H-NMR resonances of the 13C-methylenes and several base paired imino protons of tRNAPhe were obtained using 1D 13C-half filtered spectra. It was found that while SPM and BMS bind to the N(3)-H of base pairs T54-m1A58, U50-A64 and U52-A62, BES binds only to T54-m1A58 and U50-A64. This regioselectivity in the binding of the three polyamines to tRNA was correlated with their biological effects on cell growth. Using human melanoma cancer cells (MALME-3M), we found that SPM and BMS were without effect and cytostatic, respectively, while BES was distinctly cytotoxic. The latter also affected cell cycling and, at variance with SPM and BMS, lead to a distinct G1/S cell cycle arrest.
Palavras-chave : 1H-NMR of polyamines; tRNAPhe; melanoma; spermine.