A study of the effect of methylmercury on deoxyribonucleic acid (DNA) helicity using UV absorption spectroscopy

• Main Author: Somoza, Ana Jane Mari
• Format: text
• Language: English
• Published: Animo Repository 1991
• Subjects: Methylmercury; Deoxyribonucleic acid; Ultraviolet spectroscopy; Ultraviolet spectra; Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/1381; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=8219&context=etd_masteral
• Institution: De La Salle University

A pH- and concentration-dependent interaction of methylmercury with DNA was observed using UV absorption spectroscopy. Metylmercury interacts with the oxygen on the phosphate moeities of DNA at pH 5.7, 7.0 and 8.0 when the methylmercury to DNA mole ratio was 1.08 to 6.47 resulting to stabilization of the DNA double helix as was evidenced by reduction of UV absorption at 260 nm (hypochromicity). Methylmercury interacts with the amino substituents of the base moeities of DNA at pH 7.0 where the methylmercury to DNA mole ratio was 8.62 resulting to destabilization or denaturation of DNA as evidenced by an increase in UV absorption at 260 nm (hyperchromicity). At pH 5.7 and 8.0 and at methylmercury to DNA mole ratio of 8.62, hypochromicity was observed. Addition to sodium chloride in the amount required to give methylmercury to sodium chloride mole ratio of 1 in the denatured DNA recovers the original native DNA indicating preferential binding of methylmercury with chloride over that with base moeities of DNA. Melting temperature Tm of 87'C, percent GC pairs of 40.7 and percent hyperchromicity of 14.2 in 5 mM NaNO3 and 5 mM NaH2PO4 - Na2HPO4 buffer indicates that the DNA sample is relatively stable and is mainly in the two-stranded helical structure.