Interaction of ethylenethiourea with dna using circular dichroism (cd)

Soudabeh Askari,1 Sadegh hasannia,2 Soheila kashanian,3,* Zohreh shariati,4 Zahra hemati,5

1. Biochemistry department, Biology faculty, Tarbiat Modares University, Tehran, IRAN
2. Biochemistry department, Biology faculty, Tarbiat Modares University, Tehran, IRAN
3. Faculty of Chemistry, Razi University, Kermanshah, IRAN
4. Biology department, Razi University, Kermanshah, IRAN
5. Amoozesh and Parvaresh, Khanmirza area, Chaharmahal and Bakhtiari



Pesticides have been extensively applied in recent decades in agriculture throughout the world. they are powerful toxicants, which are easily absorbed and tend to accumulate onto the soil, plants, foods, ground and surface waters therefore, they can cause damages to human or animal dna. ethylene thiourea can be used as a biomarker of exposure to ethylenebisdithiocarbamates(ebdtcs), which are frequently employed as fungicides in agriculture, mainly on fruits, vegetables and ornamental plants. this compound has been reported to have carcinogen, teratogen and goitrogen effects. however, lack of in vitro studies and inadequate information about the mode of etu interaction with dna led us to conduct a study on the interaction of etu with ct-dna.


The interaction of native calf thymus dna with ethylenethiourea (etu), in 10 mm hepes aqueous solutions at neutral ph=7.2, has been investigated by circular dichroism (cd), technique.


It is found that etu molecules interacted with dna and caused induced cd spectral changes from a b-like form to a more a-like conformation.


Pure ct-dna produced a characteristic positive band around 275 nm and a negative band around 245 nm. these bands are modified when ct-dna is allowed to interact with etu. the 245 nm band loses its intensity and is shifted to zero level, while the positive band at 275 nm is increased to positive values. this increase at the ellipticity values of dna, suggesting some changes in the stacking style or orientation of the base pairs of dna and etu induces conformational changes from a b-like to a more a-like form. according to our results and pervious reports, we proposed that the etu interact with o6 of guanine by hydrogen bonding. therefore, etu is able to cause conformational changes in dna structure that may lead to dna damage.


C-dna, ethylenethiourea, circular dichroism, conformational change