Sülfonamid ve Karbazol Türevlerinin DNA/Protein Etkileşimlerinin Spektroskopik ve Moleküler Kenetlenme Yöntemleri ile İncelenmesi

Abstract

The thesis study was carried out in two parts. In the first part, the interactions of calf thymus DNA (ct-DNA), protein (HSA / insulin) and sulfathiazole (STZ), a sulfonamide derivative with antimicrobial properties, selected as a model compound from sulfa group drugs were examined by spectroscopic (absorption, fluorescence) and molecular docking methods. Due to the weak fluorescence of DNA and STZ, indirect method was preferred in fluorometric interaction studies and ethidinium bromide (EB) was used as a fluorescence probe. The interactions of STZ with DNA, HSA, and insulin were studied in pH 7.4 buffer medium at different temperatures and their binding properties according to thermodynamic parameters (G, H, S) were explained. The negative values of H and S parameters indicated that DNA and insulin were bound to STZ by hydrogen bonds and van der Waals forces, and positive values of the parameters indicated that HSA was bound by hydrophobic forces with STZ. It has been clarified that the type of non-covalent binding between STZ and DNA may be groove binding. According to the fluorescence resonance energy transfer (FRET) method, the intermolecular bonding distance was found as 3.96 nm for STZ-HSA and 3.54 nm for STZ-insulin, and it was found that non-radiative energy transfer between molecule pairs was effective. Molecular docking studies demonstrated that the STZ molecule has similar interaction and conformational tendencies for each target, such as DNA, HSA, and insulin by supporting spectral results.

In the second part, the DNA / protein (HSA) binding properties of 3-amido-9-ethylcarbazole derivatives CMR (containing morpholine) and CPR (containing piperazine), which are newly synthesized and proposed as anti-cancer agents, were examined with the same methods. Because the derivatives have fluorescence properties, direct method was used in DNA fluorometric interaction studies. It was concluded that static quenching mechanism and hydrophobic interactions according to the thermodynamic parameters play an effective role in the formation of each of the CMR and DNA / HSA and CPR and DNA / HSA complexes. In addition, the binding properties of DNA were investigated by using competition experiments of two different fluorescence probes (EB and H33258), ionic strength effect, iodide ion quenching. The results suggested that CMR and CPR entered into the minor groove binding with the A-T region of DNA. According to the fluorescence resonance energy transfer (FRET) method, the intermolecular bonding distance is 3.10 nm for CMR-HSA and 2.45 nm for CPR-HSA. It has been concluded that non-radiative energy transfer between these molecule pairs is effective. The obtained experimental data were supported and validated by molecular docking results. Both spectral and computational results show that CMR and CPR derivatives can be classified as a promising molecule in drug design for other similar carbazole derivatives.