Studies of the binding mode of TXNHCH2COOH with calf thymus DNA by spectroscopic methods

• TXNHCH2COOH was chosen as thioxanthone derivative to display the interaction to ct-DNA
• Highly increased fluorescence emission intensity was clue for the intercalative binding.
• The intercalative binding mode between TXNHCH2COOH and ct-DNA was also confirmed by melting and KI quenching studies.

In this study, a thioxanthone derivative named 2-(9-oxo-9H-thioxanthen-2ylamino) acetic acid (TX-NHCH2COOH) was used to investigate small molecule and DNA binding interactions. Absorption and fluorescence emission spectroscopy were used and melting studies were used to explain the binding mode of TXNHCH2COOH-DNA. Intrinsic binding constant Kb TXNHCH2COOH was found 6 × 105 M− 1from UV–Vis absorption spectroscopy. Fluorescence emmision intensity increased by adding ct-DNA to the TXNHCH2COOH and KI quenching experiments resulted with low Ksv value. Additionally, 3.7 °C increase for Tm was observed. The observed quenching of EB and ct-DNA complex and increase viscosity values of ct-DNA by addition of TXNHCH2COOH was determined. All those results indicate that TXNHCH2COOH can intercalate into DNA base pairs. Fluorescence microscopy helped to display imaging of the TXNHCH2COOH-DNA solution.

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