PhD Scientific Days 2019

Budapest, April 25–26, 2019

DNA-porphyrin binding mechanism investigated by single-molecule force spectroscopy

Kretzer, Balázs

Balázs Kretzer1, Prof. Dr. Miklós Kellermayer1

1 Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary

Language of the presentation

Hungarian

Text of the abstract

DNA-porphyrin binding mechanism investigated by single-molecule force spectroscopy

Balázs Kretzer1, Miklós Kellermayer1

1 Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary

Porphyrins and their derivatives have long been of interest because of their potential use in Photodynamic Therapy (PDT). They can be excited by light of an appropriate wavelength to produce reactive oxygen species. Moreover the binding of cationic derivatives - e.g., tetrakis(4-N-methylpyridyl)porphyrin - to DNA might have the potential to obstruct the replication process.
It would be important to determine the nanomechanical changes of the DNA that the binding process causes in order to describe the DNA-porphyrin interactions in more detail.
We used optical tweezers coupled with confocal microscopy to measure the nanomechanical properties of both porphyrin-free and porphyrin-bound DNA complex. Furthermore, we developed a method to investigate the changes of the DNA inflicted by the porphyrin binding.
We were able to detect the elongation of the double stranded DNA that was caused by the binding of porphyrin molecules. Furthermore, binding reaction rates were probed along a concentration gradient. The reaction rates were so high - due to the small size and high specific charge of the investigated porphyrin - that the concentration gradient proved to be a rate limiting factor.
The long-term goal is to investigate the concentration dependence of the nanomechanical changes of the DNA-porphyrin complex. Optical tweezers are the optimal tool for the measurements and the results can be backed by atomic force microscopy (AFM) experiments. In addition, we aim to develop a technique with which the kinetics of binding becomes measurable. Thus, we will be able to map the molecular mechanism of DNA-small molecule interactions by single-molecule force spectroscopy methods.

Data of the presenter

Doctoral School: Basic and Translational Medicine
Program: Cellular and molecular biophysics
Supervisor: Prof. Dr. Miklós Kellermayer
E-mail: kretzer.b1@gmail.com