Interaction of 6 mercaptopurine with calf thymus DNA--deciphering the binding mode and photoinduced DNA damage.
DNA is one of the major intracellular targets for a wide range of anticancer and antibiotic drugs. Elucidating the binding between small molecules and DNA provides great help in understanding drug-DNA interactions and in designing of new and promising drugs for clinical use. The ability of small molecules to bind and interfere with DNA replication and transcription provides further insight into how the drugs control the expression of genes. Interaction of an antimetabolite anticancer drug 6 mercaptopurine (6MP) with calf thymus DNA was studied using various approaches like UV-visible spectroscopy, fluorescence spectroscopy, CD, viscosity and molecular docking. UV-visible spectroscopy confirmed 6MP-DNA interaction. Steady state fluorescence experiments revealed a moderate binding constant of 7.48 × 10(3) M(-1) which was consistent with an external binding mode. Competitive displacement assays further confirmed a non-intercalative binding mode of 6MP which was further confirmed by CD and viscosity experiments. Molecular docking further revealed the minimum energy conformation (-119.67 kJ/mole) of the complex formed between DNA and 6MP. Hence, the biophysical techniques and in-silico molecular docking approaches confirmed the groove binding/electrostatic mode of interaction between 6MP and DNA. Further, photo induced generation of ROS by 6MP was studied spectrophotometrically and DNA damage was assessed by plasmid nicking and comet assay. There was a significant increase in ROS generation and consequent DNA damage in the presence of light.
Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Sayeed Ur
SU
Rehman
Department of Chemistry, Faculty of Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Zahid
Z
Yaseen
Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Mohammed Amir
MA
Husain
Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Tarique
T
Sarwar
Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Hassan Mubarak
HM
Ishqi
Department of Biochemistry, Faculty of Life Sciences, A.M. University, Aligarh, Uttar Pradesh, India.
Mohammad
M
Tabish
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D002417:Cattle; D002942:Circular Dichroism; D020552:Comet Assay; D004247:DNA / Q000187:drug effects* / Q000528:radiation effects; D004249:DNA Damage; D004270:DNA, Circular / Q000187:drug effects; D007454:Iodides / Q000494:pharmacology; D008027:Light; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D010957:Plasmids / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D055672:Static Electricity; D013481:Superoxides / Q000378:metabolism; D013868:Thioinosine / Q000494:pharmacology*; D014783:Viscosity
D000964:Antimetabolites, Antineoplastic; D004270:DNA, Circular; D007454:Iodides; D017382:Reactive Oxygen Species; D013481:Superoxides; D013868:Thioinosine; D004247:DNA