Studies on the interaction of copper complexes of (-)-epicatechin gallate and (-)-epigallocatechin gallate with calf thymus DNA.
The interaction of copper complexes of (-)-epicatechin gallate (ECG) and (-)-epigallocatechin gallate (EGCG) with calf thymus DNA (ct-DNA) was investigated by UV-visible (UV-Vis), fluorescence and circular dichroism along with melting studies. It was observed that both copper complexes quench the fluorescence intensity of ethidium bromide bound ct-DNA upon binding, resulting in a ground state complex formation by a static quenching process. The binding constants evaluated from fluorescence data were supported by the UV-Vis study. The values ranged from 0.84 to 1.07x10(5)M(-1) and 1.14 to 1.04x10(5)M(-1) for Cu(II)-ECG and Cu(II)-EGCG, respectively for the temperature range 21-42 degrees C with two binding sites. Thermodynamic parameters obtained are suggestive of the involvement of different modes of interaction during binding for each complex although both were found to be intercalating in nature. Circular dichroism studies and variations in the melting temperature reveal unwinding of the ct-DNA helix with conformational changes due to binding.
Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.
Kalyan Sundar
KS
Ghosh
Bijaya Ketan
BK
Sahoo
Deblina
D
Jana
Swagata
S
Dasgupta
D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000378:metabolism*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
D009942:Organometallic Compounds; D003300:Copper; D002392:Catechin; D004247:DNA; C427203:calf thymus DNA; C062669:epicatechin gallate; C045651:epigallocatechin gallate