1H-NMR structural analysis of ethidium bromide complexation with self-complementary deoxytetranucleotides 5′-d (ApCpGpT), 5′-d (ApGpCpT), and 5′-d (TpGpCpA) in aqueous solution

✍ Scribed by D. B. Davies; L. Karawajew; A. N. Veselkov

• Publisher: Wiley (John Wiley & Sons)
• Year: 1996
• Tongue: English
• Weight: 999 KB
• Volume: 38
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/(sici)1097-0282(199602)38:6<745::aid-bip6>3.0.co;2-v

✦ Synopsis

H-NMR Structural Analysis of Ethidium Bromide Complexation with Self -Complementary Deoxytetranucleotides 5'and 5'-d (TpGpCpA) in Aqueous Solution d (APCPGPT) 9 5 ' 4 (APGPCPT) 9

Complexation qf the trypanocidal drug, ethidium bromide (EB) , and the se!Pcomplementary deoxytetrarihonucleoside triphosphates, 5 , and 5'd( TpCpCpA) , in aqueous salt solution has been investigated using one-dimensional and t M udimensional 500/600 M H z 'H-nmr spectroscopy. Six hundred megahertz two-dimensional homonuclear 'H-nmr spectroscopy (nuclear Overhuiiser <flea spectroscopy) was used .f?)r a qualitative determination qfthe structures of EB binding with the deox.vtetrunucleotid~Js. Concentration dependencies of proton chemical shifts qf the molecules have been measured at constant temperatures (T = 303 or 308 K ) . Diferent successive schemes of complex ,formation between the dye molecule and the tetranucleotides have been examined bv taking into account various molecular associations in solution, viz., 1.1, 1.2, 2:l and 2:2 complexes. Equilibrium reaction constants and the limiting proton chemical shifts in the complexes have been determined. The relative contributions of different types qf complexes in the equilibrium mixture have been determined and special features qf the dynamic equilibrium have been revealed by analysis of chemical shifts as a function of both the dye and tetranucleotide concentrations. The present analysis leads to the conclusion that E B binds preferentially to the pyrimidine-purine sites ofthe tetranucleotide duplexes. The results show that the energy ofEB binding depends on the base content in the pyrimidine-purine sites of the tetramers and on the nucleotide residuals